EMISSIONS CONTROL
OF
ENGINE SYSTEMS
CONSILTANT REPORT TO THE:
Committee on Motor Vehicle Emissions
Commission on Soeioleehnical Systems
•
National Research Council
SEPTEMBER 1974
l.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
OH ice oi Mobile Source Air Pollution Control
-------
CONSULTANT REPORT
to the
Committee on Motor Vehicle Emissions
Commission on Sociotechnical Systems
National Research Council
on
EMISSIONS CONIROL OF ENGINE SYSTEMS
PREPARED BY:
James E. A. John, Chairman, Engine Systems
Naeirn A. Henein
Ernest M. Jost
Henry K. Newhall
David Wulfhorst
John W. Bjerklie, Chairman, Alternatives
William J, McLean
Charles Tobias
David Gordon Wilson
Washington, D,C.
September 1974
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NOTICE
This consultant report was prepared by a Panel of Consultants at
the request of the Committee on Motor Vehicle Emissions of the National
Academy of Sciences. Any opinions or conclusions in this consultant re-
port are those of the Panel members and do not necessarily reflect those
of the Committee or of the National Academy of Sciences.
This consultant report has not gone through the Academy review
procedure. It has been reviewed by the Committee on Motor Vehicle Emis-
sions only for its suitability as a partial basis for the report by the
Committee.
The findings of the Committee on Motor Vehicle Emissions, based
in part upon material in this consultant report but not solely dependent
upon it, are found only in the Report by the Committee on Motor Vehicle
Emissions of November 1974.
-------
PREFACE
The National Academy of Sciences, through its Committee on Motor
fehicle Emissions (CMVE), initiated a study of automobile emissions-
control technologies at the request of the United States Congress and
the Environmental Protection Agency (EPA) in October 1973, To help
carry out its work, the CMVE engaged panels of consultants to collect
information and to prepare consultant reports on various facets of mo-
tor vehicle emissions control. This Consultant Report on Emissions
Control of _Engine Systems is one of five consultant reports prepared
and submitted to the Committee in connection with the Rejxnrt by the
Cpnroittee on Motor Vehicle Emissions of November 1974, The other con-
sultant reports are:
An Evaluation of Catalytic Converters for
Control of Automobile Exhaust Pollutants,
September 1974
Emissions and Fuel Economy Test Methods and
Procedures, September 1974
Field Performance of Emissions-Controlled
Automobiles, November 1974
Mamifacturability and Costs of Proposed Low-
Emissions Automotive Engine Systems, November
1974
These five consultant reports are NOT reports of the National Academy
of Sciences or its Committee on Motor Vehicle Emissions. They have
been developed for the purpose of providing a partial basis for the
report by the Committee as described more fully in the cover NOTICE.
ACKNOWLEDGEMENTS
The authors would like to thank Drs, Robert F. Sawyer and
Nicholas P, Cernansky for their contributions to this consultant
report.
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CONTENTS
Conclusions • 1
1. Introduction ».. 3
2. Modifications to Conventional Reciprocating Spark-Ignition
(S.I.) Engines 5
3. Conventional Spark-Ignition Engine with Oxidation Catalyst—
1975 Standards 10
4. Potential of Conventional Engines with Oxidation Catalysts... 13
5. Air/Fuel Mixture Preparation 18
6. Lean Burn Sys terns 62
7. Dual Catalyst Systems 67
8. Three-Way Catalys t with Feedback , 80
9. Rotary Engines 90
10. Stratified-Charge Engines 100
11. Diesel Engines 137
12. Alternative Power Plants for Automobiles 179
13. Alternative Fuels 214
References 239
Appendices
A. Organizations Contacted by Members of the Panel of Consultants
on Engine Systems 256
B. Organizations Contacted by Members of the Panel of Consultants
on Al ternatives 259
IV
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TABLES
Table Mo. Page No,
2.1
2.2
4.1
4.2
4.2
5.1
5.2
5.3
5.4
6.1
6.2
7.1
7.2a
7.2b
7.3
7.4
7.5
8.1
Summarization of the Work of the Panel on
Interns! Comb us tion Engines .....................
Federal Exhaus t -Emission Standards
Effect of Engine Modifications on Emissions. ....
Results of 1975 California Certification
Exhaust Emission Test Summary California Division
of Highways Unclerf loor Converter Fleet.
"in Service" Fuel Economy Summary California
Division of Highways Underfloor Converter Fleet.
Test Results of a 1973 Dodge Monaco.
Cylinder- to-Cylinder Distribution Spreads
Comparison of Air/Fuel Ratio Distribution with
and without Vapipe - 1.8 Litre
Evaluation of a Carburetor with Ultrasonic Fuel
Dispersion Used on a Plymouth Duster. ...........
1974 Dodge, 360 CID, 4,500 Ibs (Ethyl tests)
Results with the Dresserator on the 1975 FTP,...
Experimental Results - Dual Catalyst System.....
Prototype 1977 Dual Catalyst System Performance
350 CID, 5,000 lb} EGR, Air, '75 FTP Low Mileage
18 Car Fleet 1977 Dual Catalyst System Performance
1977 Dual Catalyst - Closed-Loop System Performance
Results of GEM 68 System
Questor System on 1971, 400 CID Pontiac Catalina
Results of Three-Way Catalyst with EFI and
Feedback
2
6
7
14
15
16
28
37
40
41
62
65
68
70
71
73
76
78
82
V
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Table No. Page No.
8.2 Data on a Vega with Three-Way Catalyst, EFI
and Feedback 85
Comparison of Various Control Schemes (1.9 L
Engine) All Cars Equipped with L-jetronic 86
Results of Three-Way Catalyst with MFI 87
GM Results with Advanced Design Carburetors,
Feedback and Three-Way Catalyst 88
9.1 Exhaust Emissions of the 1974 Mazda with Rich
Thermal Reactor 91
9.2 Typical Deterioration Factors of Thermal
Reactor-Equipped Rotary Engines „ 94
9.3 Emissions Summary 95
9.4 Rotary with Lean Reactor 96
9.5 Emission and Fuel Consumption Characteristics
of an Experimental Open-Chamber Stratified-
Charge Rotary Engine 97
10.1 Emissions and Fuel Economy of Turbocharged
TCCS Engine-Powered Vehicle 116
10.2 Fuel Specifications for TCCS Emissions Tests,. 117
10.3 Honda Compound Vortex-Controlled Combustion-
Powered Vehicle Emissions 124
10.4 Emissions and Fuel Economy for Chevrolet Impala
Stratified-Charge Engine Conversion 125
10.5 Single-Cylinder Low Emissions Engine Tests.... 133
10.6 Volkswagen Large-Volume Prechamber Engine
Emis s ions 135
11.1 Mass Emissions and Fuel Economy from LDV
Diesel Engines - 1975 FTP 138
VI
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Table Mo. Page No_,
11
11
11
11
11
11
11
11
1 7
1 ?
12
11
1 1
13
13
13
13
,2
.3
.4
,5
,6
,7
,8
,9
.1
.2
.3
.la
. Ib
.2
,3
,4
.5
Effect of Injection Timing on Emissions
from Perkins 154 Engine in Ford Zephyr
Car (CVS Cycle)
Aldehydes and Ammonia Emissions from Different
Types of Cars
Comparison Between Opel Diesel and Gasoline
Cars . , ..
Fuel Economy in Taxi Application . .
Comparison Between Diesel and Gasoline Fuels..
Initial and Maintenance Costs and Performance
of Mercedes 1975 Cars ,
Comparison Between Exterior arid Interior
Noise Levels of Diesel- and Gasoline-Powered
Cars ,
Comparison of Odor from Diesel- and Gasoline-
Powered Cars ,
Steam Engine Characteristics
Stirling Engine Description
Batteries for Electrically Driven Vehicles.,..
Cos t of Alternative Fuels
Cost of Alternative Fuels
Physical Properties of Iso-octane and Methanol
Test Data for 15% Methanol -Gasoline Blend
Federal Test Procedure Emissions with Hydrogen
Supplemented Fuels , . , , , .
Effect of Vareb-10 on Cold-Start Emissions....
145
153
158
161
161
163
171
175
188
193a
204
218
219
227
233
231!
237
VLl,
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FIGURES
Figure No.
5.1 The Relationship of Typical Engine Emissions
and Performance to Air /Fuel Ratio ........... 19
5.2 Air/Fuel Ratio Control ...................... 21
5.3 Idle Speed Circuit .......................... 22
5.4 Fuel Metering Curve... ...................... 23
5.5 Air/Fuel Ratio Distribution ................. 25
5.6 Variable Venturi Carburetor ................. 27
5.7 Fuel Droplet Size Distribution .............. 29
5.8 Sonic Carburetor Principle .................. 31
5.9 Ford Motor Co. Estimate of Induction System
Mixture Quality Trends under Hot Operating
Conditions .................................. 32
5.10 Ford Motor Co. Estimate o£ Induction System
Mixture Quality Trends under Cold-Start and
Driving Conditions .......................... 33
5.11 Ethyl Corporation's Rectangular Hot Box Man-
ifold for a 360 CID Plymouth ................ 36
5.12 Location of Vapipe. . . . . ..................... 39
5.13 Ultrasonic Carburetor... .................... 42
5.14 Electronic Fuel Injection. . ................. 44
5.15 Air Mass Sensor ............... . ............. 47
5.16 K- jetronic System ........................... 50
5.17 (No title) .................................. 52
5 . IS Oxygen Sensor ............................... 56
5.19 Sensor Characteristic ....................... 58
VL1L
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f_igure Ho. Page.
5.20 Sensor Output 59
5.21 Optimizer Control 60
7.1 Durability Data 68
7.2 AMA Durability Test - Oxidizing and Reducing
Catalyst 69
7.3 Effect of Getter on Inlet CO and 02 74
7.4 Typical Net NOX Conversion .. 75
8.1 Conversion Efficiency of a Three-Constituent
Catalyst. 81
8.2 4-Cylinder Engine, 1.9 Liter,, L-jectronic. .. 83
8.3 Catalyst Durability. 84
9.1 IIC Conversion Efficiency Requirements....... 92
9.2 Comparison of NOX and Fuel Consumption 98
10.1 Ford Proco Sys tern. 106
10.2 Ford Proco Engine Fuel Economy and Emissions 107
10.3 Texaco TCCS Engine 110
10.4 Texaco Controlled Combustion System Ill
10.5 Texaco TCCS-Powercd Cricket Vehicle. 113
10.6 Turbocharged Texaco TCCS M151 Vehicle....... 114
10,7 3-Valve Prechatnber Engine Concept 119
10.8 Honda CVCC Engine.. 122
10.9 Fuel Economy Versus HC Emissions for 3-
Valve Prechamber Engines 126
10.10 Fuel Economy Versus NOX Emissions for Honda
CVCC-Powered Vehicles 128
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Figure No. Page No,
10.11 Ford Divided Chamber .................. . ...... 131
10.12 Comparison of Conventional and Divided
Combustion Chamber NOx Emissions . ............ 132
10.13 400 CID Large Volume Precharaber Engine.. ..... 134
11.1 Emissions from Dies el -Powered Cars
(1975 FTP) ................................... 139
11.2 Effect of EGR on the Emissions from a
Mercedes Diesel Engine ....................... 141
11.3 Effect of EGR on Opel Rekord Diesel Car
(1975 FTP) ................................... 143
11.4 Effect of Injection Timing on Emissions
(1975 FTP) ................ . .................. 144
11.5 Airborne Particulates Emitted from Diesel-
and Gasoline-Powered Cars .................. . . 147
11.6 Benzo(a)Pyrine Emissions from Different
Automotive Engines According to 1975 FTP-
Cold Start ................................... 149
11.7 Benzo (a)Pyrine Emissions from Different
Automotive Engines at 60 mph Steady Running
Conditions .................. . ................ 150
11.8 Sulfur Compounds Emissions from Different
Cars .................................. . ...... 151
11.9 HCHO Emissions for the Modified Federal Cycle
Cold S tart (MFCCS ) ........................... 154
11.10 HCHO for 60 niph Steady Running Conditions ____ 155
11.11 Comparison of Fuel Economy at Road Load for
Mercedes Diesel and Gasoline Cars,, .......... 157
11.12 Comparison of mpg for Different Cars under
Steady-State Conditions ...................... 159
11.13 Comparison of mpg for Different Cars under
City- Suburban and Average Driving Condi-
tions .................. . .....................
x
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Figure Mo. Page Ko.
11.14 Comparative Driveability of Diesel-
Powered and Other Cars 166
11.15 Exterior Noise Levels from Different Cars... 167
11.16 Exterior Noise Levels from Different Cars.,. 169
11.1? Comparison of Exterior Noise Levels for 2.2
Liter Mercedes Gasoline and Diesel Cars 170
11.18 Interior Noise Levels from Different Cars... 173
12.1 Rear View of VW with Carter Steam Engine
Mounted; The Prime Mover Showing the 4
Cy 1 inder 189
12.1 The Boiler-Burner Assembly 190
12.2 Flowchart 192
12.3 Fuel Economy-Alternative Engines 213
13.1 U.S. Petroleum Supply and Demand, 217
13.2 Emissions Data for Alcohol-Gasoline Blends
(1975 FTP) 232
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CONCLUSIONS
1. From the viewpoint of fuel economy, at least on an urban-type
driving cycle, the diesel and stratified-eharge engines appear
most attractive. Potential problem areas for these engines that
must be resolved before large-scale introduction include smoke
and participates (and possible adverse health effects), odor,
noise and a lower performance than a conventional spark-ignition
(S.I.) engine due to lower power-to-weight ratio (especially
with the diesel).
2. The three-way catalyst system with feedback control appears to
offer benefits as far as maintainability and driveability are
concerned, with only slight loss of fuel economy due to emissions
control. The dual-catalyst (Gould) system provides a tolerable
interim approach until the three-way catalyst, feedback system is
ready for producticn.
3, Regarding standards for 1978, lowering of NOX emissions levels
from 1.0 to 0,4 g/mi appears to exact a penalty in fuel
consumption of up to 35% by excluding the diesel engine. Possible
benefits to health should be weighed against this cost.
4. There are no alternative, non-internal combustion engines that
could be available in mass production for standard-size
automobiles before the 1980's.
5. The accompanying table summarizing the work of the Panel of
Consultants on Internal Combustion Engines presents emissions
levels achievable in certification for various systems, as well
as fuel economy penalty (or advantage) due to emissions controls
as measured on the Federal CVS/CH driving cycle. Projected
dates of availability for mass production of each system are also
given in the table.
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Emissions
Levels System
0,41-3,4-2.0 Oxidation catalyst and exhaust gas
reeireulation and engine modifications
Lean burn engine
Diesel
Stratified charge -
small volume prechamber with reactor
Stratified charge -
direct fuel-injected with catalyst
Wankel with lean reactor
Fuel Economy
Penalty Availability for
(relative to 1967) Mass production
5%
57.
-(251-40%)
01-10%
•(257«,-40%)
5%-10%
1976
1977
Now
Now
1980
1976
0,41-3,4-1,0 Diesel and exhaust gas recirculation
Dual catalyst (e.g., Gould) system
Three-way catalyst and feedback
Stratified charge -
small volume prechamber with reactor
Stratified charge -
direct fuel-injected with catalyst
Wankel with lean reactor and exhaust
gas recirculation
<20%-35%)
5H-1Q7.
0%-5%
lQ%-2ffi
(15%-20%)
20%
1976
1977
1978-80
Now
1980
1976
0,41-3.4-.4 Dual catalyst (e.g., Gould) system
Three-way catalyst and feedback
Stratified charge -
small volume prechamber with reactor
Stratified charge -
direct fuel-Injected with catalyst
Q%-5%
25%-30%
1977
1978-80
Now
1980
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1. INTRODUCTION
The Consultant Report on Emissions Control of Engine Systems
represents the findings of the Panel on Internal Combustion Engines
and the Panel on Alternative Engines, The first Panel was charged
with evaluating the potential of conventional, spark-ignition
internal-combustion engines and other internal-combustion engines,
such as the rotary., diesel and stratified-charge engines, for meeting
strict levels of oxides of nitrogen (NO ) control in conjunction
JC
with specified levels of unburned hydrocarbons (HC) and carbon
monoxide (CO). The second Panel was charged with assessing the
potential of alternative, more advanced automotive engines, such as
the gas turbine, Stirling, and Rankine power plants, for meeting
similarly strict levels of emissions control. Primary consideration
was to be given to cost, in terms of fuel consumption, associated
with the achievement of various NO levels by the different engine
X
systems. The Panels were to be concerned with emissions levels
attainable in certification with vehicles tested according to the
1975 Federal Test Procedure (FTP), Durability of the engine - and
emissions-control systems for 50,000 miles was of importance, with
mileage accumulation according to the certification test procedure.
Likewise, fuel economy was to be evaluated on vehilces being driven
on the FTP. Other Consultant Reports to the CMVE are to deal with
performance in customer use, alternate testing procedures, catalytic
converters, and the manufacturability and costs of low-emissions
engine systems.
The CMVE, for the purpose of this study, is interested in
engines and systems that could be available in mass production by
the late 1970's and early 1980's.
For the 1975 model year, well over 9570 of the new vehicles
sold in the United States will continue to be powered by conventional
reciprocating spark-ignition engines with add-on devices to control
emissions to the required levels. Small numbers of rotary,
-------
stratified-charge and diesel-powered vehicles will also be available.
Due to manufacturing lead times and constraints in the tooling
industry, it is clear that the conventional engine will continue
Co dominate the market, at least up to the 1980"3, in spite of
potential advantages that one or the other alternatives may have in
terms of emissions, economy, maintainability, performance or cost.
For this reason, the first sections of this report will deal with
the conventional engine, and the various add-on devices and engine
modifications that have the potential for meeting increasingly
stringent NO levels. "Later sections of the report will cover, in
depth, the rotary, stratified-charge and diesel internal combustion
engines.
The current status of development of alternative, non-internal-
combustion engines is such that at least another generation of
development will be required before any of these will have reached
the stage of being considered a suitable prototype for manufacture.
Whereas several such engines have been run in automobiles; for
example, the gas turbine, Stirling, steam and electric engines,
several major developments are necessary before these power plants
would be ready for mass production. The Panel of Consultants estimates
that 1982 is the earliest one of the alternate engines, the gas
turbine, would be ready for limited production, and even then only if
several technological advances are achieved. For this reason, the
sections of this report dealing with alternative engines must be
considered of less direct relevance to the goals of the CMVE in
their study as compared to the sections on the internal-combustion
engine.
-------
2. MODIFICATIONS TO CONVENTIONAL RECIPROCATING
SPARK-IGNITION (S.I.) ENGINES
Up to the 1974 model year, auto manufacturers for the most part
have met the exhaust-emissions standards by means of modifications to
the conventional engine. As a reference, the federal and California
standards that have been achieved in certification, all converted to the
1975 FTP, as well as future emissions standards, are given in Table 2.1.
Changes to achieve the specific standards, up to model year 1974, have
included alterations in spark Liming, reduction in compression ratio (CR),
use of leaner air/fuel (A/F) ratios, shorter choke times, improvements
in carburetion, exhaust-gas recirculation (ECR), use of air pumps and air
injection to promote exhaust reactions, and inlet air preheating. The
primary effects of these modifications on exhaust emissions are summarized
in Table 2.2 below.
Such techniques have been successful in achieving reductions in
exhaust emissions from those of an uncontrolled 1967 vehicle of approxi-
mately 8070 in hydrocarbons., 707, in carbon monoxide and 50% in oxides of
nitrogen. Accompanying these reductions in emissions has been an increa;. j
of vehicle fuel consumption. Factors such as spark retard, reduction of
compression ratio and exhaust-gas recirculation have tended to reduce
engine efficiency and, hence, degrade fuel economy. Alternately, reduc-
tions of choke times and improvements in carburetion have a beneficial
effect on fuel economy.
The overall fuel economy degradation on a sales-weighted
average due to emissions controls, from 1967 to 1973 or 1974, is between
123 -'•'
1070-15% f ' based on the vehicles being tested on the urban federal
driving cycle. Greater losses have been felt in larger cars, only small
decreases or even benefits in smaller cars.
There are several reasons why small cars have not shown the
same increase of fuel consumption as standard or large-size cars.
First, with the lower exhaust flows of smaller cars, the mass emissions
of NO and CO of uncontrolled small cars (less than 3,000 Ibs) were
x 4
less than those of larger cars (greater than 4,000 Ibs). This
^'References are listed at the end of the report (page 139)
5
-------
Federal
1967 (Precontrol)
1968
1970
1972
1973,1974
1975,1976
1977
1978
6
TABLE
2.1
Exhaust -Emission Standards
HC(g/mi)
12
6.2
4.1
3
3
1.5
0.41
0.41
C0(g/mi)
79
51
34
28
28
15
3.4
3.4
NO (g/mi)
6
NR*
NR
NR
3.1
3.1
2.0
0,4
--Not required California Exhaust-Emission Standards
1972
1974
1975,1976
2.9
2.9
0.9
28
28
9
3.1
2.0
2.0
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7
TABLE 2.2
Effect of Engine Modifications on Emissions
HC CO NOX
Spark Retard Reduce Reduce
Reduce CR Reduce Reduce
Lean A/F Reduce Reduce Increase (then decrease if
beyond A/F = 16)
EGR Increase -• Reduce
Air Injection Reduce Reduce
Shorter Choke
Time Reduce Reduce
Air Preheat Decrease Increase
-------
has meant that less EGR, for example, has been necessary to reduce
NO to required Levels.
x
Further^ pre-controlled small cars typically ran with richer
calibrations than standard or large cars. Greater improvements were
then realized with leaning out the carburetion. Finally, fuel-
metering technology for larger cars has been superior to that of -small
cars. The imposition of emissions controls has required large
improvements in fuel metering for small cars, some manufacturers
going to mechanical or electronic fuel injection. Thus, these factors
have all tended to improve economy of small cars, canceling out losses
due to other engine modifications to achieve emissions control.
The most important factors that cause increased fuel
consumption due to emissions control have been spark retard, decrease
of compression ratio, and EGR. Reduction of one compression ratio,
for example from 9:1 to 8:1, has the effect of increasing fuel
consumption by 3%-5%. A comparable fuel economy penalty has been
incurred with the use of spark retard to achieve HC and NO control.
x
Further, the use of off/on EGR to achieve NO levels of 3,1 g/mi
called for in 1973 and 1974 models has brought about an approximate
5%-6% decrease of fuel economy.
It is important to realize that exhaust emissions are
influenced by many engine variables; for good economy and low
emissions, control systems must be optimized. For example, running
lean provides benefits in fuel economy, but may result in higher 10
A
emissions, necessitating the use of EGR. The use of EGR, requiring
mixture enrichment to retain driveability, also permits an increase
of spark advance, which may recover some of the fuel economy
degradation caused by using EGR.
In general, engine modifications, such as spark retard and
EGR or the addition of an air pump, adopted to lower emissions from
1974 levels to those of 1975 models for the 49 states or even
-------
California, have the effect of degrading both fuel economy and
driveability. Thus, whereas manufacturers are certifying
vehicles with only engine modifications for production at 1975 federal
levels or at 1975 California levels, such vehicles incur a fuel
economy penalty of 57.-10% relative to 1974 vehicles. For the most
part, such systems are backup to their primary, first-choice system
which features the use of an oxidizing catalytic converter.
-------
3. CONVENTIONAL SPAIR-IGNITION ENGINE WITH
OXIDATION CATALYST - 1975 STANDARDS
A very large percentage of 1975 models sold in the United
States, both domestic and foreign made, will feature the use of an
oxidation catalyst to clean up the exhaust hydrocarbons and
carbon monoxide. Several different configurations of catalyst and
system will be used. For example, General Motors will generally
employ an under-floor pelletized catalyst bed, whereas Ford will use
a monolith located nearer to the engine. Ford will use an air putnp
on all catalyst-equipped cars; General Motors and Chrysler will use
air pumps in California cars, but only on a small number of 49-state
cars. Whereas Chrysler and Ford will use about the same carburetion
as 1974, General Motors will run. at about A/F ratio = 16, leaner
than 1974. All catalyst-equipped cars will use low lead (91 RON)
fuel (.05 g/gal) to prevent catalyst poisoning. Nineteen seventy-five
emissions-control systems will also feature improved start-up
procedures to permit rapid fuel evaporation, high energy breakerless
electronic ignition to provide more reliable ignition, and EGR to
control NO .
x
At present, it appears that virtually all 1975 models equipped
with oxidising catalytic converters will be certified for production.
Catalyst durability is such that no American-made models and only some
European models will require catalyst changes in 50,000 miles. With
lead-free fuel and breakerless ignition, there appears to be very
little deterioration in engine emissions for 50,000 miles. The chief
difficulty is deterioration in HC control with the catalytic converter.
Whereas HC conversion efficiencies are well over 95% at low mileage,
they deteriorate to 60%-70% at 50,000 miles.
Fuel-economy gains are to be experienced with the use of
oxidation catalysts. To some extent, the car can now be tuned for
optimum economy, with the catalyst cleaning up the resultant HC and CO
emissions, rather than tuning for minimum emissions and losing
economy. Chief economy gains are to be realized with elimination
10
-------
11
of some of the spark retard used in previous model years to control
HC. The limitation on the amount of spark advance with catalytic
systems is not resultant HC levels but the octane rating of the fuel
used and the resultant problem of knock. With more spark advance,
proportional EGR systems more closely tailored to the engine
requirements, better cold-start performance and, In some cases,
leaner-carburetion, large economy improvements are possible. On the
basis of data taken from durability certification cars, General
Motors reports the following improvements in fuel economy, comparing
1975 vs 1974 49-state cars in the federal test procedure:
Including Mix Change + 19.8%
Eliminating Mix Change* + 21.1%
-'Assumes 1975 mix (75% large cars) for 1974 production, where
actual 1974 production was 80% large cars,
A comparison of fuel economy for GM California 1975 cars vs 49-state
cars shows an approximate 5% degradation in fuel economy sales-
veightcd miles per gallon (SWMPG) for the California cars, due
primarily to the use of the air pump and increased EGR in California
cars. Again, results are from certification tests run on the FTP,
Somewhat lesser fuel economy improvements in certification
have been reported by the other American and foreign manufacturers.
For example, Chrysler and Ford anticipate a 5%, improvement in economy
over 1974 vehicles. It must be remembered that the above figures
represent comparisons between different model years of the same
manufacturers. Comparisons of the SWMPG of American manufacturers
for 1974 models showed the following:
GM 10.29
Ford 11.63
Chrysler 11.10
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12
The use of catalytic converters on small cars has not resulted
in a fuel economy improvement, primarily because such cars did not
suffer the penalty due to engine modifications of the large cars,
Therefore,, foreign manufacturers report fuel economy for 1975 vehicles
roughly equivalent to that of 1974 models.
It is significant to note that with the use of the catalytic
converter, most, if not all, of the 107« to 15% fuel economy penalty
attributed to emissions controls has been recovered.
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4. POTENTIAL OF CONVENTIONAL ENGINES WITH OXIDATION CATALYSTS
In examining the potential of conventional systems for meeting
the current 1977 standards of 0,41 g/mi HC, 3,4 g/mi CO and 2,0 g/mi
NO , it is of interest to look first at results achieved by 1975
California certification cars, tuned to meet levels of 0,9 g/mi HC,
9.0 g/mi CO and 2.0 g/mi NO . Table 4,1 shows data from all the
vehicles that have, at this date, been made available to the Panel of
Consultants and have completed California certification. The quoted
emissions values include 50,,000-mile deterioration factors, applied
Q
in the required certification test procedure.
Caution must be exercised in drawing conclusions from Table 4.1
manufacturers must aim at targets well below the standards to ensure
with some degree of confidence that a satisfactory mix of vehicles
will pass certification and be available to the market. Nevertheless,
these vehicles were not tuned to meet 1977 Levels, but rather the
higher California 1975 levels, so significant reduction in emissions
are possible (below those of Table 4.1),
Very little data are available on systems tuned to meet 1977
levels. General Motors has had two fleets of Oldsmobiles in service
with the California Highway Department. Both fleets were tuned to
meet 1977 levels, and equipped with oxidation catalysts, one fleet
with air pumps, one without. Results are shown in Table 4,2. Mileage
accumulation for these data were not according to the AMA durability
schedule of the FTP.
The data shown in the above mentioned tables provide
convincing evidence that 1977 levels can be achieved by model year
1977. One method of achieving the required reductions in emissions
from California 1975 certification would be via engine modifications,
such as spark retard, with the loss of fuel economy. However,
improvements are available which would not necessarily increase fuel
consumption over that of a 1975 California car.
13
-------
Manufacturer
1.
2.
3.
4.
5.
6.
7-
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
GM
GM
GM
AMC
AMC
AMC
AMC
AMC
AMC
AMC
AMC
AMC
AMC
AMC
AMC
AMC
AMC
14
TABLE 4,1
Results of 1975 California
Vehicle
Vega, 2,750# I.W., 140 CID
Automatic
Cutlass, 4,500#, 350 CID,
Automatic
Delta 88, 5,000#, 350 CID
Hornet 232 A, 3,500#
Hornet 258 A, 3,500*
Homet 232 M, 3,500#
Gremlin 232 A, 3 ,000*
Pacer 258 M5 3,5QQ#
Matador 304 A, 4,500#
Gremlin 304 M, 3,500#
Hornet 304 M, 3,500#
Matador 304 A, 4,500#
Matador 2V-360 A, 4,500#
Matador 2V-360 A, 4,500??
Matador 2V-360 A, 4,500#
Matador 4V-360 A3 4,500#
Matador 4V-401 A, 4,500#
Certification,
HC
0.4
0.4
0.7
0.28
0.18
0.46
0.22
0.26
0.46
0.49
0.64
0.23
0.51
0.36
0.45
0.42
0.51
CO
6.8
2.3
6.7
7.5
5.9
7.3
6.2
6,3
3.7
6.3
7.4
3.6
4.3
3.2
2.9
2.6
3.8
NOX
1.6
1.4
1.6
1.5
1.5
1.9
1.5
1.9
1.9
1.7
1.9
1.9
2.0
1.9
1.6
1.9
1.4
MPG
20.1
12.6
12.4
15.6
14.4
13.8
16.8
14.9
13.1
13.0
12.8
12.3
11.9
11.9
11.6
11,7
10.4
REFS. 9, 10
-------
15
TABLE 4.2
Exhaust Emission Test Summary
California Division of Highways
Underfloor Converter Fleet
13 Oldsmobiles (No air pumps)
Average Test
Mileage
194
4108
8222
12296
16022
20535
24976
249502
29635
No. of
Cars
13
13
13
5
13
5
3
12
2
19/:>
HC
0.19
0.20
0.24
0.25
0.24
0.23
0.21
0.23
0.19
EPA Grams
CO
1.90
2.22
2.14
2.83
2.87
2.13
3.16
2.12
2.23
/Mile
NOX
1.75
1.86
1.84
1.75
1.79
1.72
1.93
1.86
2.20
12 (AIR) Oldsmofoiles
Average Test
Mileage
230
4426
8820
13857
No. of
Cars
12
12
12
12
1975 EPA Grams/Mile'
RC
0.30
0.31
0.31
0.35
CO
0.9i
0.98
1.21
1.50
1,48
1.62
1.72
1.58
NOTES:
1
Certification test procedure
Slave canister procedure^ CM reports that 1 g/mi CO
should be added to CO levels due to variations in
test procedures
REF. 11
-------
16
TABLE 4.2 (Continued)
"In Service" Fuel Economy Summary
California Division Of Highways
Underfloor Converter Fleet
13 Oldsmobiles (No Air Pumps)
Average Fuel Economy (MPG) 10.6
Fuel Economy Range (MPG) 10.2 - 11.0
12 (AIR) Oldsmobiles
Average Fuel Economy (MPG) 11.0
Fuel Economy Range (MPG) 10,0 - 11.S
Ho comparable fleets of production vehicles available
for comparison.
-------
17
Seventy to eighty percent of the unburned HC and CO of a 1975
catalyst-equipped vehicle is given off during the first two minutes
after cold start. Methods to reduce the amount of fuel used during
choking will both lower emissions and increase fuel economy. The
1975 emissions-control systems will use reduced choking times and
will employ provisions for using exhaust heat for early fuel
evaporation. Systems that have promise of effecting even better
control during start-up include electrical heating of a charge of
fuel, electronically operated chokes, use of a small catalyst during
start-up that will reach operating temperature in a short time, etc.
Further reduction in emissions is possible by increasing the quantity
of active material in the catalyst and in some cases, by increasing
catalyst volume.
To reduce NO levels below the 1977 level of 2.0 g/mi while
jC
retaining control of HC and CO, increased amounts of EGR will be
necessary. The resultant richer mixtures required to maintain flame
speeds and driveability will lead to fuel economy penalties. The
latter may be minimized by using greater spark advances, but this will,
in turn, require extra control of HC.
Except for small, low-powered cars, where NO outputs are
basically low due to the low flows required, it is doubtful whether
a significant number of vehicles with conventional engines and
oxidation catalysts would be able to reach levels <£ 0.41/3.4/1,5 g/mi
without additional control measures or without excessive fuel
economy penalties.
-------
5. AIR/FUEL MIXTURE PREPARATION
5.1 Iii t r o due t i on
For emissions control to 1975 levels, considerable improvement
in mixture preparation and delivery has been achieved. To reduce
engine emissions and also to prevent an excessive burden on the
oxidation catalyst, reductions of variations of A/F ratio from
cylinder to cylinder and over the driving cycle have been necessary.
Further improvement in mixture preparation will be required to
meet stricter standards. A closer A/F ratio control is essential for
lower NO emissions because all known NO control methods result in
x x
poor driveability and fuel economy if the mixture is allowed to vary
widely. NO catalyst technology specifically requires very high A/F
jC
ratio control which cannot be met with good presently used carburetors,
Another approach to minimize emissions and to maintain or
improve economy does not involve the use of catalysts. In a warm
engine, the optimum A/F ratio for minimizing all three pollutants is
on the very lean side of stoichiometry; e.g., at A/F ratios larger
than 18-20:1 as illustrated in Figure 5.1 where HC, CO, and NO
j£
emissions are plotted against A/F ratio. With current technology
in mixture preparation and engine design, however, very lean mixtures
rob the engine of horsepower output and increase fuel consumption,
shown also in Figure 5.1. Engine and mixture-preparation technology
are under development which will extend the range of adequate fuel
economy and power output of lean mixtures as shown by the dotted
lines in Figure 5.1. In this section, a discussion of improved
mixture preparation methods will be presented which will be required
for advanced emissions-control systems on conventional engines.
Included will be advanced design carburetors, fuel injection and
feedback control systems. Later sections of this report will deal
with the emissions and fuel economy potential of lean engines and
NO catalytic systems.
18
-------
19
Stoichsometric
Conventional Engine
— Lean Burn Engine
10
AIR/FUEL RATIO
FIGURE 5.1 The Relationship of Typical Engine Emissions and
Performance to Air/Fuel Ratio. The Vertical Scale is Linear
and Shows Relative Rather than Absolute Values for Each Param-
eter.
-------
20
5.2 Carburetors
a. Conventional carburetion— The amount of fuel issuing from
the jet situated in a Venturi of a carburetor increases at a faster
rate than that corresponding to an increase in air intake. The
mixture formed by a simple carburetor thus becomes richer as the
engine aspirates more air and, consequently, a mixture which is
correctly proportional for high air (full load) will be too lean at
lower air flows (idle and part load). Figure 5.2 illustrates the A/F
ratio control of such a simple carburetor as a function of Venturi
vacuum (or the equivalent parameter engine rpm at part load).
An engine equipped with such a carburetor will run too rich
at medium to full-load operation if excessive leaning out at idle is
to be avoided, and for this reason such an engine would be highly
polluting and poor in fuel consumption.
Modern carburetors achieve better A/F ratio control over the
full speed/load range by using idling and full-load Venturis, idle
speed and transition orifices to supply additional fuel at idle,
acceleration pump, etc,
Figure 5.3 illustrates a cross section of a Weber
12
multijet carburetor.
A typical calibration curve which is conventionally used to
provide for the mixture needs of an engine operating under all
spead-load conditions is illustrated in Figure 5.4 for a single-barrel
carburetor as used on the Vega 4-eylinder engine and with a carburetor
13
used on Chevy 6's in the 1960's (dotted line). The throttle is
gradually opened from A(a) to D(d) and held wide open from D(d) to
E(e) and F(f), As the engine slows down the D-E-F line the A/F
ratio leans out because less air is being pulled through the
carburetor. The engine comes to a lugging stall at point F.
-------
21
0.36,—
2345
DEPRESSION IN THROAT (Ib/in2)
FIGURE 5.2
-------
22
Gam
Gm
FIGURE 5.3 Idle Speed Circuit
Gam - Idle Speed Air Jet
Gm - Idle Speed Fuel Jet
G - Main Fuel Jet
1 - Idle Speed Mixture Orifice
2 - Transition or Progression Orifice
3 - Idle Mixture Adjusting Screw
U - Throttle Setting or Idle Speed Adjusting Screw
Source: Reference 12
-------
23
DC
10
11
O 12
S 13
- 15
<
16-
17 -
19
0.5 1 234 567
ib AiR/min
FIGURE 5.4
9 10 11 12 13
Source; Reference 13
-------
24
Pre-emission-control carburetors were able to reproduce
the A/F calibration curve within a band of +57= to 10%; present
carburetors have narrowed the band to+3%. These figures are,
however, deceptive because they do not reflect the dynamic A/F ratio
changes which occur during acceleration, deceleration modes, changes
in altitude, air and fuel temperatures, air humidity, etc., which all
affect A/F ratio control,
A more serious problem with conventional carburetors is the
variation in A/F ratio distribution from one cylinder to another
cylinder. This problem arises from the fact that normal aspiration
in a fixed Venturi carburetor results in relatively large fuel
droplets which tend to segregate in the manifold. This segregation
is more pronounced with cold engines, and under idle or low-load
operation of the engine where the low air velocity through the
Venturi results in large droplets which are difficult to distribute.
Variations as large as 207= in the cylinder-to-cylinder A/F
ratio distribution have been reported for some European and American
14 15
engines (see Figure 5.5). * The resulting emissions are high
in HC and CO and can lead to premature catalyst failures. Improved
carburetor manifold designs have reduced the A/F ratio spread to
about 5%.
The cost of the more complex carburetors has been increasing,
A simple single-barrel carburetor costs approximately $5 to $10; the
more complex multibarrel carburetors, with altitude compensation
and other ancillary controls, may cost as much as $40. The fuel
economy and emissions control which can be realized with these
carburetors are marginal when compared with new mixture preparation
devices, and it is reasonable to assume that the conventional
carburetor will be gradually phased out by other devices in the
foreseeable future.
-------
25
BSFC
Brake
Specific
Fusl
Consumption
15.5 13.3
FIGURE 5.5 Air/Fuel Ratio
Distribution in an 8-Cylinder
Engine.
Source: References 14, 15
-------
26
b. Variable Venturi carburetors andconstant depression
carburetors — Variable Venturi and constant-depression carburetors
overcome the problems of low air velocities which were described in
the previous section by varying the area of the Venturi in accordance
with the weight of air that is required per unit time by the engine.
The Venturi can thus provide depressions and air velocities which are
adequate to cause fuel to flow and be dispersed under most operating
conditions of the engine. These carburetors also feature a variable
area fuel orifice that varies with the changes in area of the Venturi
in such a manner that the desired A/F ratio is provided at all times.
Figure 5.6 shows an example of such a carburetor.
The piston valve can slide up and down in its guide and
change the air passage or Venturi area. As the valve changes the
area of the Venturi throat, it also moves the tapered metering pin
in the fuel jet opening, and thus it provides a varying fuel jet
orifice. The dash pot reduces the movement of the piston and
prevents rapid upward movement when the throttle is operated
rapidly.
The low pressure or partial vacuum at the throttle end of
the Venturi throat causes air to flow through the piston vent until
the pressures in the vacuum chamber and Venturi throat are equal.
The lower side of the flex diaphragm has atmospheric pressure
acting on it, and the force due to the pressure differences lifts the
piston up or down.
Thus, for each air flow rate through the Venturi there is a
corresponding position of the piston valve, and a particular value of
the vacuum in the throat of the Venturi. The size of the fuel jet
orifice and the taper of the metering pin are made so that the fuel
flow with any given position of the piston valve is the desired flow.
Most carburetor companies are working on some version of
the Variable Venturi (V.V, ) carburetors. Most have chosen combination
-------
27
FIGURE 5.6
Source: Reference 16
-------
28
carburetors with one barrel operating with a fixed Venturi while the
other performs as a V.V. version. This version of carburetor appears
to have the best chance of being interfaced with electronic controls
as will be discussed later.
Table 5.1 summarizes some results which were achieved with
a 1973 Dodge Monaco with a 1974 360 CID V-8 engine and the
experimental Holley model 2880 Variable Venturi carburetor.
TABLE 5.1
A/F ratio control +31
HC = 1.48 g/mi
CO = 10.28 g/mi
NO =1.8 g/mi
5C
Spark timing - 60° BTC
No air pump
10% EGR
Fuel Economy - 11 mpg
A fixed Venturi 4-barrel carburetor of similar design has
higher HC and CO emissions (approx. HC - 2.5 g/mi, CO - 20 g/mi) and
equivalent fuel economy. NO remains unchanged.
x
In spite of these improvements, the Variable Venturi
carburetor will not achieve the A/F ratio control required for the
three-way catalyst and simultaneous control of HC} CO, and NO .
j\,
c, Sonic carburetors -- The size of droplets produced by
a carburetor varies approximately inversely with the velocity of
air flowing through the Venturi. Figure 5,7 shows the relationship
between air velocity and fuel droplet diameter entering the intake
manifold, J The droplets which are achieved at sonic velocities
(approximately 1000 ft/sec) and above are so small that little
segregation occurs within the carburetor and intake manifold, and,
-------
29
800,
700
tr 600
D
> 500
I
O
400
UJ
>
oc
300
200
100
0 10
FIGURE 5.7
20 30 40 §0 60
FUEL DROPLET SIZE (microns)
70
Source: References 18, 19
-------
30
consequently, sonic carburetors have much lower cylinder-to-cylinder
A/F ratio variations than conventional carburetors.
The Dresser carburetor is the best known sonic carburetor
and considerable work is being performed throughout the industry
to develop its potential.
The Dresser carburetor or "Dresserator" is a Variable Venturi
tUE
21
20
carburetor with a mechanically actuated fuel distribution bar. The
principle is shown in Figure 5.8.
The device shows promise of improving atomization, mixture
quality, A/F distribution, and control. It achieves these
improvements by:
Designing the entrance/exit geometry to produce sonic flow at
the carburetor throat which results in superior fuel atomization.
Introducing fuel over a large surface area which is subjected to
sonic air-flow levels.
, Passing the A/F mixture through a shock wave to atomize the fuel
and improve mixing.
, Eliminating flow distortion caused by downstream throttle plates.
Coupling the throttle with a linear fuel-control valve to achieve
constant A/F control.
Eliminating the choke, although some enrichment is necessary
during start-up.
The mixture quality which can be achieved with sonic
carburetors is comparad with conventional production carburetors3 EFI,
s tratified-charge engines (PROCO) and liquid propane (LPG) or liquid
natural (LNG) cars in Figures 5,9 and 5,10 for various points in the
. , 22
induction system.
-------
31
Fuel Flow
Sonic Flow •:•:•_
Subsonic Fiow
Air Inlet
Fuel Distribution Bar
Supersonic Flow
Shock Wave
FIGURE 5,8 Sonic Carburetor Principle,
Source: Reference 21
-------
Good
Poor
32
LPG or LNG
EFI
Carburetor Riser
! ntake
Valve
Spark
Plug
FIGURE 5.9 Ford Motor Company Estimate of Induction System
Mixture Quality Trends Under Hot Operating Conditions.
Source: Reference 22
-------
33
Good i—
LPG or LNG
Poor
FIGURE 5.10 Ford Motor Company Estimate
of Induction System Mixture Quality Trends
Under Cold Start and Drive Conditions.
Source: Reference 22
-------
34
With exception of LHG and LPG, sonic carburetion provides the
most homogeneous mixtures and thus improved distribution.
Sonic carburetion is still in the development stage and a
variety of problems remain to be resolved among them:
Actuation forces under sonic conditions are high and lead to
rapid component wear,
Need for altitude and temperature compensation,
Manufacturability and durability,
Cold start where sonic velocities cannot be achieved,
d. Hp_t:-spot carburetors --As was shown in Figures 5,9 and 5,10,
LNG and LPG produce better mixtures than gasoline because they evaporate
more readily than gasoline in the operating temperature range of the
engine. Similarly, cylinder-to-cylinder A/F ratio variation could be
eliminated by vaporizing and mixing the gaseous gasoline with the
incoming air. Several difficulties are associated with this
approach are:
The heat required to vaporize all fuel under full-load conditions
is over 2KW and cannot be supplied by the automotive electric
power.
The fuel evaporator has to be designed to prevent simultaneous
heating of the incoming air and associated volumetric efficiency
losses,
, Vapor lock has to be prevented,
Hone of the fuel evaporation systems which are presently under
evalutation has resolved these problems satisfactorily.
Most automobile manufacturers use hot spots or early fuel
evaporation (EFE) devices to help during cold start. These are
turned off as soon as the engine reaches operating temperature and
-------
35
therefore do not influence the cylinder-to-cylinder A/F ratio
distribution of the warm engine.
The Ethyl Corporation, Shell Laboratories in England, and
British Leyland ' * are experimenting with evaporative heaters
which are kept in operation during the full operating range of the
engine. The objective of these approaches is to improve the A/F
ratio distribution to allow ultralean operation of the engine under
all load conditions.
The Ethyl Corporation's hot-box manifold is shown in
Figure 5.11.
The hot box is situated underneath the primary barrels of
a Quadrajet carburetor and sunk into the exhaust manifold crossover.
The fuel/air mixture of the primary barrel passes through the hot
box under all driving conditions; the air/fuel mixture of the
secondary barrel, on the other hand, bypasses the hot box under
all conditions.
Since the air-flow velocities of the secondary barrel
provide for good fuel distribution without evaporation, the resulting
A/F distribution is better under all driving loads. The main flow
of air is not heated by this system and, therefore, the volumetric
efficiency is maintained. The cylinder-to-cylinder variation of
this carburetor mounted on a 350 CID Plymouth engine is shown in
23
Table 5,2.
The A/F ratio spread with this carburetor is approximately
3% under idle and 1.6%, at 30 mph. This is an improvement of a factor
of 1. over a conventional carburetor. Further improvement are
anticipated from a variable Venturi arrangement in the secondary
barrel.
-------
36
a-j n
"
Recycle
FIGURE 5,11 Ethyl Corporation's Rectangular Hot
Box Manifold for a 360 CID Plymouth.
Source: Reference 23
-------
3?
TABLE 5.2
Cylinder-To-Cylinder Distribution Spreads
Speed
Idle
15
30
50
Cruise
A/F1 F/A2
16,3
17.5
17.3
16.6
.061
.05?
.058
.060
A Distribution
A A/F A F/A
0.50
0,49
0.28
0.47
.0020
.0016
.0009
.0016
A/F = air/fuel ratio
2
F/A = fuel/air ratio
-------
38
Typical emissions results for a modified* 1974 Dodge 4,500 Ib
360 CID engine are (g/mi) :
HG -- 1.33, can be improved to 1,1-1,2
CO -- 7.80, can be improved to 6-7
NO -- 2.76, can be improved to 2.3-2.5
Jv
Fuel economy -- 10.7, can be improved to 11.2 mpg
Base-line figures for the conventional Quadrajet carburetor
are (g/mi):
HC -- 2.8
CO -- 26.0
RO -- 2.5-2.7
x
Fuel economy -- 11,0
The Shell Laboratories' (England) Vapipe approach is to use
the exhaust heat to heat and evaporate all the fuel under all engine
24
operating conditions. Heat is transferred to the carburetor with
heat pipes which are connected to the exhaust manifold (see Figure 5.12).
The results are similar to those achieved by Ethyl Corporation:
The engine can be operated at very lean A/F ratios without losing
driveability.
The A/F cylinder-to-cylinder distribution is excellent (Table 5,3).
•'•'Equipment: Carter Thermo-Quad Carburetor
Electric choke assist
Ethyl hot-box manifold
EGR -- control with Venturi and throttle position sensor
Timing 5° ETC
-------
39
FIGURE 5,12 Location of Vapipe,
Source: Reference 24
-------
TABLE 5.3
COMPARISON._OF AIR-FUEL RATIO DISTRIBUTION
WITH AND WITHOUT VAPIPE - l.B LITRE (110 CU.IN.) CAR
Test
Condi tion
Idle
Road Load
30 raph
48 km/h
Road Load
50 mph
80 km/h
Road Load
70 mph
112 km/h
Full Throttle
30 mph
48 km/h
Full Throttle
50 mph
80 km/h
Standard Car - Standard Setting
Overall
Tailpipe
13.2
14.2
15.4
15.0
14,3
13.6
Cyl.l
13.1
15.4
15.8
15.3
14.7
13.3
Cyl.
2 & 3
13,4
13,5
15.2
14,9
13.5
12,9
Cyl, 4
12,9
14.2
15.6
16.1
15.3
14.8
Vapipe Car - Standard Setting
Overall
Tailpipe
13.1
13.4
15.8
14.8
13.6
13.5
Cyl.l
13,1
13,5
15.8
14,8
13.7
13.8
Cyl.
2 & 3
13.1
13,4
15,8
14.7
13.6
13.5
Cyl, 4
13.1
13.4
15.8
14.7
13.9
13.6
Vapipe Car - Lean Setting
Overall
Tailpipe
16.5
16.3
17.9
16.6
17,1
16.6
Cyl.l
16.4
16.6
17.7
16,7
17.4
17.0
Cyl.
2 & 3
16.5
16.3
18.0
16.6
17.2
16.6
Cyl. 4
16.4
16.5
17.9
16.6
17.5
16.7
-------
41
The emissions of all three pollutants are lowered.
Fuel economy is improved over that of the same engine with a
conventional carburetor,
e. Carburetor with ultrasonic fuel dispersion — Recently
several carburetor-like devices have been proposed which use
ultrasonic energy to achieve good fuel dispersion and cylinder-to-
cylinder mixture distribution. One version is being developed by
Autotronics. Another version, which has been proposed by Dr. A. K.
f\f
Thatcher and Dr. Ed McCarter, Florida Technical University, uses
a magnetostrictive transducer at frequencies of 20,000 Co 40,000
Hz to break up the fuel stream into very small droplets. The device
is shown in Figure 5.13. Fuel injectors spray fuel onto the surface
of the horn of a magnetostrictive transducer where the fuel is
atomized into very small droplets which are mixed with the flowing
air. The device was evaluated on a Plymouth Duster with a 225 CID
slant six engine and is summarized in Table 5,4.
5.4
Duster with Duster with
Ultrasonic Device Std. Carburetor
(g/mi) (base-line) (g/mi)
HC - 0.44 4.9
CO - 0.88 6.6
NO - 1.0 + 301 3.0 to 8.0
MPG - 22 18
The base-line HC and NO emissions seem overstated; however,
the improvements in emissions levels with this system are believable,
The large difference in fuel economy cannot be justified by what is
-------
MAGNET
DRIVING COILS
FIGURE 5.13 Ultrasonic Carburetor,
FUEL
INJECTOR
Reprinted courtesy of Popular Science, 1973, Popular Science Publishing Company
Source; Reference 26
-------
43
known about the device alone. The drawbacks of the system, as
presently implemented, are high power consumption, noise, complexity,
and thus, high cost. Therefore, it seems that the objective of
better fuel dispersion may be accomplish more easily with a sonic
or hot-spot carburetor or fuel injection.
5.3 Fuel Injection Systems
a. Electronic fuel injection - speed and density systems — The
oldest electronic fuel injection system (invented by the Bendix
Corporation approximately 15 years ago and perfected and manufactured
by Robert Bosch, Germany) measures air density and engine speed to
derive the air quantity drawn in by the engine and to inject the
appropriate amount of fuel.
Robert Bosch started production of this system In 1967 and
has presently 1.5 million of the D-jetronic EFI types in the field
installed on 40 different 4-, 6-, and 8-cylinder engines. The
27 28
principle of the system is illustrated in Figure 5.14. '
The air quantity drawn in by the engine is determined by
measuring the engine rpm and electronically multiplying this figure
by the engine displacement constant. A manifold vacuum pressure
transducer and an ambient air temperature sensor convert the air
volume to standard temperature and pressure (STP). The electronic
control logic processes these signals and injects the appropriate
amount of fuel into the intake manifold through fuel injectors which
are positioned on top of the cylinder heads. Fuel is fed to these
injectors through a well-regulated, pressurized fuel rail.
The D-jetronic system is a pulsed injection system where the
quantity of fuel is modulated by changing the length of the injection
pulse. The D-jetronic system sells to the original equipment market
29
(OEM) in Europe for approximately $120 for a 4-cylinder version.
For this reason, it has found only limited application in spite
-------
44
Injector
rpm
Manifold
Density
Air Flow
Air Flow {!b/min} =
Displacement (I3/rew) X
Speed (rev/min) X
Cylinder or
Manifold Density
ECU
Fuel ^
\
\
I
mm.
)?
\"
j
{
\
I
Z
1
I
—
^
f
_
\
i
]
i
H
M
w/
-f
\
FIGURE 5.14
Source: References 27, 28
-------
45
of the fact that it has been offered in Europe for over seven years.
The Bendix Corporation in the United States has developed a similar
speed density system but has failed to find wide acceptance again,
27
mainly due to the high cost of the system.
There is considerable controversy about the benefits of
electronic speed density fuel injection systems:
It is well established that the maximum power output for a given
engine can be improved; for example, with electronic fuel
injection (EFI), a 208 liter Daimler Benz gasoline engine
delivers 185 hp at wideopen throttle (WOT) and only 150 hp with
30
a carburetor. This advantage is due to the better volumetric
efficiency and full power enrichment with EF1, (The EFI
manifold has fewer obstructions for the inrushing air.) This
advantage is mainly realized at full throttle, particularly
with high speed European engines - most current U.S. cars
rarely operate at full load and would not benefit from EFI.
Electronic fuel injection can offer better cylinder-to-cylinder
A/F ratio distribution for poorly designed engine manifolds
and engine types which have difficult induction problems. An
example is the air cooled opposed piston engine used by
14
Volkswagen. This engine has long intake manifolds and a
cylinder firing sequence which makes it difficult for some
cylinders to get the correct charge. Traditionally, this engine
was carbureted rich in order to assure that all cylinders had
adequate mixtures. The consequences were high emissions.
Electronic fuel injection solved the problem by supplying
each cylinder with the appropriate amount of fuel. Electronic
fuel injection, in itself, does not have any advantage over a
well carbureted engine. For example;
-------
46
31
Saab 2 Liter Engine 3,000 Ib, Automobile
(Raw Engine Emissions)
HC CO NOX MPG
D-jetrcmic
(dual catalyst) 1.18 40,9 2.19 16
Carburetor
(dual catalyst) 1.9 40,7 2.4 17.7
Close loop K-jetronic
(3-way catalyst) 0.9 8.14 2.2 19,3
Electronic fuel injection improves cold-start performance, again,
particularly for European engines with simple carburetors and
choke systems. U.S. cars do not benefit from this feature.
Some European manufacturers "have opted to use EF1 rather than
to design an advanced carburetor because it was cheaper to do so,
In summary, D-jetronic EFI can offer some advantages in A/F
ratio distribution for a few engines with difficult manifold and
firing sequence problems. It improves cold start and power output
at WOT, It does not offer fuel economy and emission advantages over
well carbureted engines,
b. Electronic fuel injection - air mass system (L-Jetronic)—
In 1972 Robert Bosch produced the L-jetronic system, a second
generation EFI3 which monitors the quantity of air drawn in by the
engine directly with an air mass sensor as shown in Figure 5.15. This
32-34
system has been described in several publications. The air
mass is measured by a flap situated in the main air stream. The
force of the flowing air on the flap is balanced against the force
of a return spring. To eliminate rapid pulsation, the device
incorporates an air chamber and another flap which acts as a dash
pot damper (stabilizer volume). A butterfly valve in the air flow
measuring flap absorbs backfiring pulses. The flap angle is converted
into voltage by the potentiometer which is attached to the axis of
the flaps. This device eliminates the pressure and temperature
-------
47
FIGURE 5.15
Source: References 32, 33, 34
-------
48
sensors of the D-jetronic system and simplifies the electronic
circuit.
The rest of the L-jetronic system is similar to the D-jetronic
system. It has a pressure regulated fuel rail, port injection, an
additional injector for cold start, etc. The L-jetronic system,
however, offers the following improvements:
Improved start-up which leans out the engine faster.
Deceleration control.
Simultaneous injection of all injectors (rather than sequential)
which allows the injection pulse length to increase and to reduce
the injection time error. For example, at fall load, the
injection pulse is 8 msec with the L-jetronic and 4 msec with the
D-jetronic EFT. Since the pulse rise time is 1.6 msec, the
errors introduced at a 4-msec pulse width are considerable.
The L-jetronic EFI is more rugged and measures air more
accurately. For example, the air-mass meter is independent of
barometric and back pressure changes which throw off the calibration
of the D-jetronic system, and it monitors air flow independent of
EGR.
The L-jetronic system is approximately 10% cheaper than
the D-jetronic system, viz. s approximately $110 for a 4-cylinder
European engine versus approximately $120 for the equivalent
D-jetronic system. Because of these advantages, most users of
D-jetronic EFI, particularly Volkswagen, will switch in 1975 to
L-jetronic EFI.
The raw emissions of the L-jetronic system are lower than
those achieved with D-jetronic EFI; 1975 Federal standards can be
met comfortably. For example, a 1.6 liter air-cooled Volkswagen
, 35
engine measured:
-------
49
HC - 1.16 g/mi
GO - 7.1 g/mi
NO - 1.22 g/mi
5k
The L-jetronie system does not seem to offer significant
35
fuel economy advantages. Volkswagen reports, for example 18,3 miles
per gallon in 1974 vs. 17.8 miles per gallon in 1975 for their Type 2
air cooled engine. Other models show slight increases in 1975,
In summary, the L-jetronic system reduces emissions when
compared to the D-jetronic system. These improvements are due to
better air measuring inputs, improvements in the start~ups
deceleration controls, and injection timing. The L-jetronic system
is capable of meeting the 1975 federal standard but cannot meet 1975
California standards without oxidation catalysts or thermal reactors.
Fuel economy remains equivalent to D-jetronic or well carbureted
engines.
c. Mechanical fuel injection.(K-jetronic system) -- The
^> £" Q "J
K-jetronic system * uses the intake air volume as the controlling
variable to determine the A/F ratio and to eliminate the need for
electromechanical conversion. Figure 5.16 shows the schematic of
the system.
The floating flap air-sensor plate is mounted on a lever
having a balanced weight attached to the short end. The flow rate
of intake airlifts the plate until an equilibrium is reached
between air flow and hydraulic counter pressure which acts on the
lever through a controlled piston. In this balanced position, the
plunger maintains a certain position in the fuel distributor, thus
opening small metering slits, one for each engine cylinder. The fuel
supplied by a pressurized fuel rail system passes through the slit
openings to the injection valves. The correct amount of fuel is
provided by the slit openings, than in the injection valve as in
-------
50
Injection
Valve
Starting
Valve ~j
Injection
! Line
i Fuel-Air Regulator
and Flow Divider
7
Fuel Pump
FIGURE 5.16
Source: References 36, 37
-------
51
electronic fuel injection.
Hydraulic counter pressure acts on the top of the control
piston to influence the fuel quantity needed by the various operating
conditions of the engine. By exerting more force on the top, the
plunger travels less, and less fuel flows to the injection valve.
The opposite is true when the pressure is released. The control
pressure is varied by control-pressure regulators, one regulating
according to engine and outside temperature and the other according
to accelerator pedal position. The controlled pressure regulator for
temperature compensation maintains the correct A/F ratio by enriching
the mixture during engine warm-up. As the engine reaches its normal
running temperature, it leans out the mixture. This control-pressure
regulator contains a bimetal spring which acts on a spring-loaded
diaphragm (see Figure 5.17). For example when the engine is cold,
the diaphragm keeps the inlet open to maintain a minimum pressure
on the plunger of approximately 2,3 atm. As the heating coil of
the bimetal spring heats up, it permits the diaphragm to close off
the inlet opening, thus increasing the control pressure and leaning
out the mixture.
The control-pressure regulator for throttle vavle position
compensation is mounted on the throttle valve shift (see Figure 5,17),
According to accelerator movement, the control pressure on top of
the plunger is again changed to provide the correct A/F ratio. When
the throttle is at idle, the control pressure is maintained at 3 atm,
at mid-range throttle opening, 3.7; and at wide open throttle, 2.9;
thus increasing fuel delivery as the throttle is depressed.
The K-jetronic system has a starting valve which provides
additional fuel during start-up conditions, and has a number of
significant advantages over both electronic fuel injection systems:
-------
52
t
2.7-3.1
bar
To
Tank
t f
u.
2 — 1
To t
Tank 3.7 bar (WarmJ
8. Control pressure regulator lor throttle valve position compensation.
A—idle position; B - rnidrsnge petition; C—full-throttle position.
t I
'•; o o
"'. Contfol pressure regulator for
wjrn^.running compensation.
A -cold position; S—warm position
FIGURE 5.1?
9 Fuel accumulator prevents vapor 10- Auxiliary air device assures good
locking of the system. 8iMuel fatio duri"8 deceleration.
Source; References 36, 37
-------
53
It is a simpler system and is understood by mechanics.
It is lower in cost. The OEM cost for the system in small
quantities is approximately $100 and is likely to be lowered as
the volume production commences,
The K-jetronic system is slightly better than the L-jetronic
system in controlling emissions and improving fuel economy
because it minimizes time lags associated with sensor signals
and fuel-injection pulses.
The K-jetronic system is capable of meeting the 1975 federal
standards, but it cannot meet the 1975 California standards
without a catalyst.
In summary: The K-jetronic system provides the same advantages
over carburetors as the other two electronic fuel-injection
systems; namely, higher power output under wide open throttle
conditions, less air induction problems and better cold start.
The fuel economy is approximately the same as with the L-jetronic
system, although Audi, Volvo, and Saab claim some minor
advantages, Volvo claimed that the fuel economy of their two-
liter, carbureted engine increased from 17 mpg to 19 mpg for
Q O
the same engine with a K-jetronic fuel-injection system.
39
Saab, on the other hand, showed an example during the
Washington presentations of a carbureted engine with better fuel
economy than one with K-jetronic injection.
This difference in opinion illustrates the danger of
extrapolating the emission and fuel economy results achieved
with one type of intake-manifold-engine combination as compared
to another even if the same carburetor or fuel-injection system
is used in both.
-------
54
The emissions from K-jetronic injection are equivalent to those
of the L-jetronic system.
5,4 Feedback Systems
The A/F ratio of an operating engine Is influenced by the
temperature of the air, temperature of the fuel, the humidity of
the air, the chemistry of the fuel which affects density surface
tension and viscosity, the absolute pressure of the air, the back
pressure of the engine and the shifts in calibration of fuel
metering rods, orifices, etc. Of all these variables, only a few are
monitored with present fuel-metering devices:
The advanced carburetor will have altitude compensation but has
no sensors for air temperature, humidity, etc.
, The electronic and mechanical fuel-injection systems will also
incorporate altitude compensation and air temperature measurements
but do not monitor variables such as humidity, fuel viscosity,
etc,
For these reasons, open-loop fuel metering cannot be correct under
all conditions of vehicle operation. Only a closed-loop system which
monitors either the composition of the exhaust gases or some engine
output parameter, such as horsepower output, can maintain the A/F
ratio within correct limits by constantly supplying corrective
signals to the primary F/A metering device,
Two main approaches are being pursued at the present time:
Systems based on the exhaust-gas composition, specifically,
systems monitoring the oxygen content of the exhaust system;
Systems based on engine output parameters, particularly horsepower
output.
-------
55
a> Feedback systems based on the 02 - exhaust gas sensor and
EFI, mechanical (continuous) fuel injection or electronic
carburetors — In 1971, Robert Bosch proposed a new exhaust-gas
composition sensor which provides a strong variable voltage signal
40
around the stoichiometric composition of the A/F mixture. The
sensor output was used to close the feedback loop with the L-jetronic
electronic control unit and to correct the fuel injection pulses and
maintain the A/F ratio at exact stoichiometric composition. The
control achieved with this feedback was typically an order of
magnitude better than that achieved with advance carburetors or
approximately +0.370 vs the +3% achieved with the best carburetor
system.
The heart of this control system is the oxygen sensor. Such
a sensor is shown in Figure 5.18. It consists of a doped ZrO tube
with phatinura electrode on each side. One side of the sensor is
exposed to the exhaust manifold gases, the other to the atmosphere.
The sensor operates as an electrochemical oxygen concentration cell
with ZrO solid electrolyte. The platinum electrode acts as a
reaction site for the reaction:
CO + 0 C07 and
HC + 0 H20 + C02 ,
and the sensor output is determined by the oxygen partial pressure
of these reactions or the concentration of oxygen on the surface
of the senor rather that the "free" oxygen concentration in the
exhaust stream.
As the mixture goes from rich to lean, the partial pressure
12
of oxygen on the surface will change by a factor of 10 or more and,
according to the Kernst equation, a step-like voltage change of
almost one volt will appear across the electrodes of the sensor as
-------
56
{exhaust}
Zircondioxide
Platinum Surface
FIGURE 5.18
Source: Reference 40
-------
57
shown in Figure 5.19. A signal will always occur at stoichiometrie
exhaust gas compositions regardless of temperature or exhaust gas
flow rate. The rise time of the signal is very rapid (milliseconds).
The sensor has to be brought to at least 400 C before a useful
signal appears and the output is temperature dependent as in Figure
5,20. By choosing the control point at 500 mV or below, the
temperature sensitivity can be eliminated because temperature
changes occur mainly at the rich end of the output.
The problems which plagued the oxygen sensor a year ago
thermal cracking, aging, and seal leaks, have been virtually
eliminated, and Bosch in Germany and UOP in the U.S. claim to have
sensors which can be guaranteed for 12,000 miles or more. The
evidence submitted to support these claims was convincing.
The oxygen sensor feedback loop can be used in conjunction
with the L-jetronic EFIS the K-jetronic mechanical injection system
or electronic carburetors. The cost of feedback-control systems may
decrease rapidly because they may eliminate many presently used
ancillary control such as fast chokes, altitude compensation} air
pumps, EGR, etc. The feedback control is very exciting new technology
with great potential to achieve Low emissions with low fuel
consumption and control system cost.
b. Feedback system based on engine output sensors -- Dr. P.
42
Schweitzer has proposed to use an engine feedback signal to vary
the mixture ratio of the engine under all driving conditions. The
principle of the control or "Optimizer" system is illustrated in
Figure 5.21.
In this version of the control system, the intake manifold
system is provided with an auxiliary air intake passage. A dither
plate continuously oscillates to change the air intake within narrow
limits. As the mixture composition changes, the engine speed
fluctuates within narrow, but well-defined limits. These variations
-------
58
f.OOOi-
£ 800
E
tfl
s
LU
600
I-
O
g 400
200
0,8 0.9 1.0 1.1 1.2
X
FIGURE 5.19 Sensor Characteristic,
Source: Reference 40
-------
E 800
I-
D
O
ir 600
O
400
200
400 C
400
TEMPERATURE ("O
700
AtR/FUEL RATIO
1'IGURE 5.20
Source: Reference 4L
-------
60
To Engine
FIGURE 5.21 Optimizer Control.
Source; Reference 42
-------
61
in engine speed are monitored by a deceleration/acceleration sensor
(the Ceisigj the derivative of rpm information) and fed into the
control logic. The conOrol logic adjusts the main air intake to the
engine in such a way that the change maximizes engine rpm. In this
fashion} this control optimizes horsepower output of the engine under
any driving condition and thus minimizes fuel consumption,
Dr, Schweitzer has made preliminary calculations of the
system and claims lower emissions with improved fuel economy, but the
system has not been tested on a car.
The optimizer control is probably useful for minimizing fuel
consumption irrespective of engine emissions. Used in conjunction
with a normally tuned carburetor, operating around stoichiometry,
the emissions would probably be high because the optimizer control
would tend to operate at the maximum power point which occurs at the
rich side of stoichiometric.
The optimizer control may have more merit in conjunction
with advanced carburetor or fuel-injection systems which maximize
the power output on the lean side of stoichiometric. In this
case, good fuel economy may be coupled with low hydrocarbon and carbon
monoxide emissions* An example would be a combination of optimizer
control with a sonic or hot-spot carburetor. It seems, however,
mutually exclusive to optimize fuel economy and minimize NO with this
x
method. Therefore, the usefulness of this feedback control will be
small to achieve KO^ emissions below 2 g/rai.
-------
6. LEAN BURN SYSTEMS
Maximum rates of NO formation occur at F/A equivalence
A
ratios about 0.9 (fuel lean), Figure 5.1. Significant reduction in
NO can be obtained by operating much leaner than this. Further, at
x
lean mixtures, excess available provides for complete
combustion of CO and HC and potentially low levels of these pollutants
in the exhaust gas stream. Advantages in fuel economy can be
realized by running lean, as long as means are taken to ensure
complete combustion of the charge. At very lean A/F, as shown in
Figure 5.1, HC levels start to increase as the quench zones become
thicker and misfire is approached. Further, systems that use lean
mixtures are generally limited by an exhaust temperature which can
lead to high HC emissions. Retarding timing and reducing the
compression ratio to achieve higher exhaust temperature and lower
HC emissions leads to fuel economy penalties.
Conventional carburetors and induction systems are not
adequate to maintain reliable operation at mixture ratios of 17:1 and
leaner. It is especially important for lean operation to have a
homogeneous mixture delivered to each cylinder at the same A/F ratio,
techniques to achieve such mixtures have been described in Section 5;
namely, the Ethyl system, Shell Vapipe and Dresser carburetor.
Results from the Ethyl system, featuring a hot-box manifold,
were presented on pages 33,36 and 37. When this system was modified
to include an exhaust lean thermal reactor, with overall system A/F
ratio 17:1, emission levels in Table 6.1 were achieved.
43
Table 6.1
1974 Dodge, 360 CID, 4500 Ib (Ethyl tests)
With reactor
HC 0.55
CO 5.0
NOX 1.40
62
-------
63
Fuel economy, as measured on a cold-start 1972 test procedure, was
107o to 15% better than that of the base vehicle.
The Shell Vapipe system is designed for very lean operation.
with h-oniogeneity achieved by fuel vaporization. Data have been
obtained on a 1.8 liter Morris Marina of 2,500 Ib inertia weight with
manual transmission. This vehicle is made for the European market
so has no EGR, and very little in the way of emissions controls except
for the Vapipe, Results of the average of 6 tests on the 1975 FTP
44
are
HC
CO
NO
X
MPG
A/F
4.
5.
1.
22.
16.
9 g/mi
9 g/mi
5 g/mi
6 MPG
5 to 1
Improvement in fuel economy has been achieved out to A/F ratio of
20:1 although at these very lean ratios3 two spark plugs are
necessary, with as much as 80 advance. A problem that must be
overcome with this system is the time required to bring the heat pipe
into operation (2 minutes).
The most promising system for obtaining the advantages of
lean operation through improved carburet ion appears at present to
be the Dresserator. The Dresserator carburetor is a variable-throat,
supersonic nozzle, operating choked for manifold vacuum of less than
3 inches of mercury. Cold start is possible at A/F ratios of 17,5:1
without the use of a choke, A/F ratios of 20:1 can be used without
operational difficulties. Results with the Dresserator on the 1975
FTP are shown in Table 6,2,
Dresser claims 6073 reductions in HC with the use of an enlarged
exhaust manifold, presumably resulting in increased exhaust reactions.
-------
64
TABLE 6.2
A. 1971 Ford Galaxie, 4,500 Lb.3 9:1 CR, 35L CID (Tests at Dresser)
Baseline
EC
CO
NO
2-3 g/mi
40 g/mi
4-5 g/mi
MEG 10.5
With Dresserator & Enlarged
Exhaust Manifold
HC
CO
ND_
A
MPG
0.3
4-5
1.2 - 1.7
11
g/mi
S/mi
g/mi
With Dresserator
at A/F 18:1
No Vacuum Advance
HC 0.8-1 g/mi
CO 6-8 g/mi
NO 1-1.5 g/mi
X
MPG 11
B. 1973 Chevrolet Monte Carlo, 4,500 Ib., 350 CID, no EGR
(Tests at GM) (Conventional Exhaust)
HC 0.849 g/mi
CO 3.95 g/mi
N0x 1.915 g/mi
MPG 11.51
46
C. Results from EPA (75 FTP)
2600cc,
47
Ford Capri, retarded timing
Chevrolet Monte Carlo, retarded timing
as above
HC CO NOX MPG
0.68 5.8 1.21 18.2
1.11 5.1 1.56 12.8
REFS. 45, 46, 47
-------
65
Ford currently has an extensive program underway to develop
the Dresser type carburetor. Results at Ford with a 4,500 lb
48
inertia-weight Galaxie, 351 CID, no EGR, indicate the following:
HC 0.70 g/mi
CO 4.17 g/mi
NO 1.93 g/mi
X
MPG 10.7
(Results on 75 FTP)
In general terms, these results are consistent with those of GM,
EPA and Dresser.
The versions of the Dresser carburetor used to obtain the
data quoted above are mostly research tools, and not suitable for
production. Many significant problem areas remain, including
difficulties in precisely controlling the throat area with the
large forces involved, wear of linkages and cams, correct location of
fuel intake, and operation during unchoked conditions (wide-open
throttle). Ford is working on three versions of the sonic carburetor.
one with annular throat and two with rectangular throat. Several
years of development effort are needed before this carburetor can be
considered ready for large-scale production.
Nevertheless, the Dresserator system, without catalyst or EGR,
can meet California 1975 standards, and, possibly with the addition
of an exhaust thermal reactor and improved inlet manifold, meet
levels of 0.41/3.4/2.0, Fuel economy at these emission levels should
be equivalent to that of a 1975, 49-state model car.
-------
7. DUAL CATALYST SYSTEMS
To reach Levels of NO below 1.5 g/mi while retaining the basic
x
components of the 1975 catalytic system will require the use of a
reduction catalyst. The typical system will consist of a NO catalyst
X
located near the engine exhaust manifold, an oxidation catalyst down-
stream, with air injection prior to the oxidation catalyst. Carburetion
must be rich to provide a reducing atmosphere for the NO catalyst.
X
In such systems, during the start-up phase, air is injected upstream
of the HO catalyst, with the reduction bed acting as an. oxidation
Jv
catalyst during the start-up period.
F/A ratio must be carefully controlled for satisfactory operation
of the NO catalyst. Too great an input of CO to the bed will lead to
X
excessive formation of ammonia; too small a concentration of CO will not
provide the correct reducing atmosphere required. Further, it is
desirable to avoid lean transients when the catalyst is up to
temperature, which may lead to excessive temperatures on the reduction
bed and, at least for some catalysts, cause failure.
Several techniques have been used to control the ratio of CO to
0 in the inlet gas stream to the reduction catalyst. Certainly,
one way is the use of improved carburetors which much enable control
of F/A to within 67a over the operating regimes of the vehicle. This
has generally been the approach of the auto manufacturers, with results
using noble-metal catalysts as shown in Table 7.1 below.
An accumulation of data on performance of NO converters developed
X
by various catalyst manufacturers and tested on General Motors vehicles
49
is shown in Figure 7,1 Even the most attractive catalyst from this
chart, curve L, was over the CO standard after 8,000 miles (Figure
7,2). More recent low-mileage data from GM on dual catalyst systems
are shown in Table 7.2a,b. Fuel economy for the base 1975 vehicle
is 12 mpg. it can be seen that} for small cars, results on the best
experimental vehicles indicate levels under 0,41/3.4/1.0 up to 10,000
to 20,000 miles with fuel economy between 0% and 5% worse than 1975
66
-------
67
TABLE 7.1
Experimental Results - Dual Catalyst System
Manufacturer
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Ford Galaxie, 351 CID
49
Ford Galaxie, 351 CID
49
Ford Galaxie, 400 CID
General Motors, 5,000 IW
350 CID, EG!50
General Motors 5,000 IW,
350 CID, EGR?0
British Leyland, Austin
Marina^l
British Leyland , Austin
Marina ^ 1
British Leyland, Austin
Marina-* 1
52
Nissan, 119 CID, Datsun
2750 IW
52
Nissan, 119 CID, Datsun
2750 IW
53
Toyota, 2,500 IW, 1.6 liter
Mileage
0
9,000
0
10,000
22,000
0
8,000
125000
0
3,000
0
8,000
12,000
16,000
20,000
24,000
0
6,740
10,720
0
10,875
0
6,600
0
4,600
11,700
20,700
0
11,800
18,300
0
5,000
HC
0.8
1.2
0,7
0.7
1.0
0.6
1.0
1.2
0.36
0.41
0.31
0.38
0.94
0.84
0.66
0.8
0.39
0.53
0.58
0.15
0.38
0.19
0.36
0.09
0.27
0.30
0.39
0.21
0.33
0.57
0.11
0.17
CO
2.9
6.2
3.0
3.4
7.0
0.9
1.5
2.0
1.9
2.4
2.8
3.4
4.4
7.6
3.4
6.8
1.32
1.71
1.7
0.67
L.8
2.49
1.51
1.08
0.73
0.93
1.67
1.38
1.1
4,07
1.89
1.12
MOX
0.6
0.7
0.7
0.8
1.0
0.4
0.5
0.7
0,41
0.56
0.24
0.24
0.38
0.34
0.36
0.36
0.29
0.27
0.64
0.45
0.85
0.35
0.23
0.33
0.39
0.48
0.68
0.30
0,31
0.39
0.43
0.49
-------
1.0r-
O
4,000
8,000
12,000 16,000
AM A Miles
20,000
24,000
28,000
FIGURE 7.1 Durability Data on General Motors' KOX Catalysts. Emission Durability
Test Results, Dual Catalyst Emission Control Systems. 1975 Federal Test Procedure.
OC3
Source: Reference 50
-------
69
1.0
0.8
f 0.6
O 0.4
0.2
0
1975 FTP BAG DATA
10 i—
O
O
1.0
0.8
1 0.6
OJ
I 0.4
0.2
0
I I
TUNEUP
0 4 8 12 16 20 24 28 32 36 40 44 48
AMA MILEAGE IN THOUSANDS
FIGURE 7.2 AMA. Durability Test Oxidising and Reducing Catalyst.
Source: Reference 50
-------
TABLE 7.2a
Prototype
1977 Dual Catalyst Systern Performance
350 GIB, 5,000 Ib , EGR, Air, '75 FTP, Low Mileage
Sy^atejn
NO
HC
CO
NO
MPG
De ve 1 opmen ta 1
0.33
2,5
0.35
11.8
0.26/0.37 2.0/3,2 0.3/0.45 11.4/12.1
Durability
15
0.30
2,1
0.28
10.1
0.17/0.48 1.1/3.8 0.19/0.35 8.7/12.4
-------
TABLE 7.2b
18 Car Fleet
1977 DLLS! ^Catalyst -System-Performance
350 CID, 5000 ib , EGR, Air, '75 FTP
A/F - 14/1
System
Manifold + U.F.
No,
12
Ay_g._ Mileage HC
231
CO
MPG
0.36 1.9 0.41 8,5
0.33/0.39 1.2/2,9 0.30/0,51 7.8/9.9
3091
0.41
2,4
0.56
9.5
Manifold
314
0.29
2.3
0.58
9.3
0.25/0,33 1.9/3.0 0.52/0.64 8.2/10.3
-------
72
vehicles. Durability results are not as encouraging for large cars
with higher engine NO emissions. The cause for the rapid decrease
•A
in NO converter efficiency with mileage accumulation is not well
x
understood; how much is due to earburetion problems, or to poisoning
or overteiaperature is not precisely known.*
It appears that the amount of work and effort being performed
on the dual-catalyst approach by the major manufacturers is somewhat
diminished over that of two years ago. This may be due either to
effort being pursued on other, more promising systems, or to a
decision to wait with the expectation that alternate standards for
NO will be legislated.
/c
Other approaches involving the use of a reduction catalyst
are being worked on by Gould and Questor. Each of these systems is
designed to carefully control the CO/0 ratio to the NO catalyst. In
•£. X
the Gould system, an 0 getter is used upstream of the reduction
catalyst. In the current Gould configuration, the getter consists of
a small, noble-metal oxidation catalyst. The getter is located in the
same can as the metallic nickel-based NO converter, with an oxidation
X
catalyst located downstream. The getter lowers the 0,. concentration
entering the NO bed to approximately 0.1% over the range of operating
X
conditions experienced in the CVS test (Figure 7.3). This would then
compensate for the variabilities associated with today's conventional
carburetors. The latest Gould reduction catalyst (GEM 68) gives over
90% next SO conversion (Fig. 7,4) when operating at 1250 F over a
range of CO/0 of 2 to 6 (corresponding to A/F ratio of 14.2:12.7).
Eesults of this system are given in Table 7.4.
To reduce HC levels to 0.41 g/mi, it would be necessary either
to use a larger or improved oxidation catalyst or to improve
•'•'To overcome problems associated with carburetor variability, GM has
run a dual-catalyst system with feedback control featuring an oxygen
sensor and variable Venturi carburetor (Table 7,3).
-------
TABLE 7,3
1977 Dual Catalyst - Closed Loop
System Performance ^^
350 CID, 5,000 LB Inertia Weight with
Oxygen Sensor and Variable Venturi Carburetor
Low Mileage (Average of Two Tests)
HC CO NO MPG
-
0.27 0.83 0,25 11.9
-------
74
8.35
7.00
5.72
o
O 3.55
£
O 2.68
o
o 2.20
1-
g 1.88
LU
°- 1.20
0,55
0.00
GETTER OUTLET
TIME
TiME
5.0
4.0
33
o
3.0 O
X
2.0
1.0
0.0
0.0
FIGURE 7.3 Effect of Getter on Inlet CO and 02 During Portion
of CVS Test. Test Conducted on 351 CID Ford Torino, Automatic
Transmissions
Source: Reference 54
-------
C/3
QC
o
CJ
X
o
90
80
70
60
o
-------
76
TABLE 7.4
Vehicle
73 Datsun 610, IW 2,500 Ibs.
No EGR, Manual Transmission
Test at Gould
Net NO
x
Conversion
Mileage Efficiency CO NOX HC*
3.149 0.354
1.917 0.356
1.906 0,384
5,600
10,249
15,381
85.2
86.0
84.5
25,580 85.5 3.18 0.382
*HC were measured incorrectly and are not included.
Same, Test at EPA after
25,580 miles
Average of 3 tests
HC
CO NOX Economy
0.98 2.93 0.41 21.5 MP
REF. 55
-------
77
carburetion. Both approaches are now being pursued by Gould.
Preliminary results with the Gould system on a large ear3 1971
Ford Torino, indicate NO levels of approximately 0.6 g/mi up to
A
25,000 miles, with no EGR. Fuel economy of the large car was
equivalent to that of a 1973 model. Gould's experimentation to date
has been with stock vehicles, retaining timing while resetting the
carburetors to give the desired rich carburetion. It would appear
that if this system were to be applied to a 1975 vehicle with timing
and other adjustments for optimum economy, some improvements in
economy would be attained. Conservatively, it would appear that
levels of 0,4/3.4/1.0 in standard vehicles could be realized with
economy no worse than 5%-10% beloxtf 1975 catalyst vehicles. For
small cars, 0.41/3.4/0.4 could be attained with the Gould system with
economy approximately the same as 1975 models of the same weight.
With the Questor approach, the ratio of CO/0 going to the NO
converter is controlled with a rich thermal reactor instead of a
getter. Thus,the Questor system consists of a rich thermal reactor5
followed by a metallic, nickel-based NO converter, followed by
X
another thermal reactor for cleanup of HC and CO. Controlled air
is injected into the exhaust ports and before the final oxidizing
thermal reactor. Durability tests of the Questor system are shown
in Table 7.5. Fuel economy was 8.2 mpg, about 14% worse than EPA
results for average 1974 vehicles in the 5,000-pound weight class.
Questor is currently testing a newer, more durable reduction
catalyst which will enable leaner operation (although still on the
rich side of stoichiometric). Results on a Datsun tested at 2,750-
pound inertia weight gave> at 8,103 miles:
HC 0.16
CO 2.97
NO 0.28
x
-------
78
TABLE 7.5
Questor System on 1971, 400 CID Pontlac Catalina.
Mileage HC CO NOX Comments
0 0.085 3.03 0.365
18,483 0.400 2.66 0.380
23,142 0.235 1.56 0,617 NO catalyst replaced
35,946 0.158 3.045 0.419
50,024 0.294 2.986 0.283
REP. 56
-------
79
Economy here was L8.2 mpg, about equivalent to that of the average
1974 vehicle in that class.
It is felt that improved carburetion could help economy of
both the Gould and Questor systems. Both systems appear capable of
being certified at levels below 0.41/3.4/1,0,
-------
8. THIEE-WAY CATALYST WITH FEEDBACK
8.1 Introd nc t ion
Under carefully controlled conditions, a single-bed catalyst is
able to reduce all three automotive emissions, HC, GO and NO , to
levels of 0,41, 3.4 and 0.4 g/mi, respectively. Current three-way
catalysts of this type must be operated with the engine close to
stoichiometric, as shown in Figure 8.1. Control to within +0,1
A/F ratio is required for successful operation. With the successful
development of the 0 sensor and feedback control, which allows the
required A/F ratio control (Section 5) intensive efforts are underway
to develop a three-way catalyst with the required durability. This
three-way catalyst system with feedback has several advantages over
a dual catalyst system: with only one catalyst, the problem of
catalyst warm-up and cold-start emissions is alleviated; operation
at stoichiometric rather than fuel-rich leads to improved fuel
economy; no air pump is required since enough 0 is present in the
exhaust stream; and, feedback control at stoichiometric provides a
self-maintaining feature, compensating for minor variations in
engine parameters.
^'2 Three-Way Catalyst with Electronic Fuel Injection (EFI)
and__Fee d b a c k
Many manufacturers haw been able to achieve 1978 levels at
low mile age', using the Q sensor feedback and L-jetronie fuel
58
injection. Typical results are shown in Table 8.1.
80
-------
81
100
40
Rich
14.5 150 15.5 Lean
AIR/FUEL RATIO
FIGURE 8.1 Conversion Efficiency of a Three-
Constituent Catalyst.
Source: Reference 57
-------
82
TABLE 8.1
Volkswagen
Bosch
Daimler -Ben;:
HC
CO
x
0.3
0.3
0.4
1.2
1.7
1.8
0.2
0.3
0.4
4 cylinder, 1.9 liter
8 cylinder, 4.8 liter
Robert Bosch has the most advanced durability results and claims
that 20,000-mile durability has been demonstrated with a 2,300 Ib car
and 1.9 liter engine with the values shown in Figure 8.2. After that
period, the NO emissions started to rise for unknown reasons. Bosch
x
also made the claim, based on the results of bench tests (Figure 8.3),
that better catalysts are now available and that durability of
25,000 miles or more will soon be demonstrated. The data of Figure
8.2 were obtained with the catalyst dated 10/10/73 in Figure 8.3;
59
the catalyst dated 4/2/74 clearly exhibits better performance.
Ford has been experimenting with an in-house developed
EFI system and 0 feedback with the following results for a fresh
catalyst:
HC
CO
Feed gas 2.9 22
After catalyst 0.1 2.0
No EGR
and for aged catalyst (100 hrs)
NO
x
4.2
0.5
Feed gas
After Catalyst
No EGR
HC
3.18
0.11
CO
24
0.68
HO
x
5.0
1.34
Life tests continue.
-------
83
0,4
A
en
O 0.2
10,000
20,000 25,000
3.4
O
O
0.4
x
O
0.2
25,000
FIGURE 8,2 ^-Cylinder Engine,
i.9 Liter, L-Jetronic, DeGussa OM721,
Fuel Economy 18.7 mpg, Weight of
Car 1050 kg.
Source: Reference 59
-------
84
600
400
Q.
O
200
10.10,73
4.2.74
0 100
200 300
TiME (hours)
400 500
600
0.61—
18.6.73
O
10,10,73
4,2,74
0 100
200
300 4 00
TiME (hours)
FIGURE 8.3 Catalyst Durability.
500 600
Source: Reference 59
-------
85
TABLE 8.2
a. Vega EFI Emission and Economy Results (Low Mileage)
3000 Ib I.W.
EC CO NO
x
Average of 5 emissions tests: 0.23 g/mi 2.58 g/mi 0.32 g/mi
Fuel Economy: 20.43 mpg @ 0.35 g/mi ^- NO (EGR)
21.42 mpg @ 0.90 g/mi #=- NOr(No EGR)
x
Base: 20.50 mpg for '75 Calif. @ 1,4 NO
X
20.32 mpg for '75 Federal @ 2.1 NO
x
b. Chevrolet 350 C.I.D., V8, 4,500 Ib I.W. (Low Mileage)
MPG
HC
0.56
0.47
CO
5.1
4.6
NO
x
0,96
0,77
11.5
Not available
REF. 57
-------
86
TABLE 8,3
Comparison of Various Control Schemes (1.9 L Engine)
AH Cars Equipped with L-Jetronic
Car 1
Car 2
Car 3*
Car 4*
Stoichio-
tnetric
Ratio
Spark Advance
Percent EGR
1975 Model
1.05
O
4
3-10
Lean
1.15-1.2
o
8
Double ignition
8
Lean
1.04
o
8
8
1.0
o
4 delay
0
*Cars 3 and 4 have feedback control
HC
0.57
0.15
0.2
0.15
CO
6.67
2.9
3.02
1,72
NO
1,59
0.88
1.16
0.13
Fuel Cons, 100%
121%
100%
89%
-------
8?
General Motors provided data on a Vega equipped with a three-
way catalyst, EFI and feedback as shown in Table 8,2.
Most manufacturers agree that fuel economy of the 0 sensor -
L-jetronic feedback control is improved over open-loop controls and
that 1978 standards can be met with minimum fuel penalty If the three-
way catalyst aging problem is resolved.
Bosch provides an interesting comparison of various control
systems in Table 8.3. The superiority of feedback is evident.
8.3 Three-Way Catalyst with Mechanical Fuel Injection (MFI)
and Feedback
The 0 sensor output requires the addition of a simple electronic
control unit and an additional solenoid-operated fuel pump to
modulate fuel pressure in the control pressure loop of the K-jetronic
mechanical fuel injection device. The 0 sensor feedback system with
K-jetronic now becomes somewhat more expensive than the equivalent
L-jetronic feedback control.
Many manufacturers report that they were able to achieve 1978
MO standards at low mileage; however, failure occurred because
jC
of three-way catalyst aging after less than 10,000 miles. Typical
results are shown in Table 8.4 .
Saab
Audi
Volvo
HC
0.1
0.28
0.25
Table
CO
1.7
1.0
0.8
58
8.4
NO
X
0.21
0.4
0.25
MPG
19.3
16.0
No durability data is available.
No U.S. manufacturer reported data with the K-jetronic feedback
system.
-------
88
8.4 Three-Way Catalyst with Carburetor andFeedback
All U.S. manufacturers and some foreign carburetor manufacturers
are developing carburetors whose settings can be continuously
adjusted with electrical error signals from an exhaust gas sensor.
Most electronic carburetors are of the variable Venturi category
although some work is reported with sonic carburetion. This approach
ia logical since feedback control makes sense only with better
cylinder-to-cylinder distribution than can be achieved with conventional
carburetors. W carburetors, sonic carburetors, and hot-spot
carburetors can provide the needed improved A/F ratio distribution.
Results from GM with advanced design carburetors, feedback and
the three-way catalyst are given in Table 8,5 (all at low mileage).
TABLE 8,5
Car Carburetor HC CO NO MPG
x
4000 I.W., V8 Mod. Quad 0.28 4,85 0.54 11.7
4500 I.W., V8, 350 CID IFC 0.17 5.5 0.69 11,5
To summarize;
In all cases, fuel economy of three-way catalyst systems is good,
as is driveability. Fuel economy could be improved further by
the complete elimination of EGR; this may not be possible with
the large U.S. engines.
The durability of the 0? sensor is established; the durability of
the three-way catalyst is not proven and cannot be predicted.
The tests of Bosch suggest, however, that a durable catalyst
may be achievable.
-------
89
The cost of feedback control systems may be attractive in
comparison with more conventional systems because of possible
elimination of many presently used ancillary controls such as
fast chokes, altitude compensation, air pumps, EGR, etc.
The feedback Control is a new technology with great potential
to achieve low emissions with low fuel consumption and
control-system cost.
-------
9, ROTARY ENGINES
9.1 In t r o du c tion
The chief advantages of the rotary engine as an automotive power
plant lie in its smoother operation fewer number of parts and
higher power-to-weight ratio, in comparison to a conventional piston
engine. However, the engine has a high surface-to-volume ratio,
contributing to higher HC emissions and lower thermal efficiencies
in comparison to equivalent piston engines. Bare-engine HC emission
levels of current rotary engines are approximately four times those
of equivalent piston engines, whereas CO and NO levels are roughly
the same as those of piston engines,
The emissions-control system used on 1974- Mazda rotary engines
featured a rich exhaust thermal reactor to control HC emissions, with
the engine operating at an air fuel ratio of approximately 13:1,
Exhaust emissions measured in 1974 California certification by EPA.
are given in Table 9.1, as well as data from Toyo Kogyo on the same
model.
Because of the above-cited problem with high HC emissions and
high fuel consumption, there does not appear to be a concerted
movement in the industry towards rotary engines. Though a few
manufacturers have increased their efforts on rotary engines, most of
the increased effort has gone into feasibility studies. Ford has
terminated such a feasibility study during the past year.
9.2 Near-Term Systems
Emissions-control systems currently used on rotary engines are
similar to those used on conventional piston engines; namely,
catalysts or thermal reactors and EGR. There is some concern about
the durability of the catalyst-equipped systems since the HC loading
is so much higher than that of conventional engines. Figure 9.1
illustrates this problem. With base-engine em ssions of 8-10 g/mi
HC catalytic converter efficiencies of approximately 90% are required
90
-------
91
TABLE 9.1
Exhaust Emissions of the 1974 Mazda with Etch Thermal Reactor
HC CO NO MPG
x
1974 California EPA certification 2.4 19 0.9 10.4
1974 Production average 2.5 14 1.3 11.8
3,000 Ib inertia weight
Engine displacement 80 CID
Manual transmission
KEFS. 61,62
-------
92
100
> 90
o
LL
LL
LU
2
o
DC
LU
>
% 80
0 2 4 6 8 10 12
BARE ENGINE EMISSIONS (g/mij
FIGURE 9.1 HC Conversion Efficiency Requirements,
Source: Reference 63
-------
93
to achieve exhaust HC levels of 0.90 g/mi (California interim 1975
level). There is clearly little margin for deterioration.
Thermal reactor systems do not appear to have this problem;
deterioration factors for these systems are shown in Table 9.2.
However, the rich reactors currently in use incur a fuel penalty,
as was shown in Table 9.1, A summary of results from General Motors
is given in Table 9.3. It can be seen that, at least at low mileage,
fuel economy of catalyst-equipped rotary engines approaches that of
equivalent 1975 vehicles equipped with conventional engines.
Toyo Kogyo is developing a lean-reactor system. This system
uses an A/F ratio of 16.5:1 to 17:1. Results are shown in Table 9.4,
9.3 Long-Term Systems
Some work is being done on more advanced rotary engines systems.
Most of this effort is being spent on adapting the stratified-charge
concepts to the rotary engine. Both open-chamber and divided-chamber
concepts have been tried with reasonable results. Table 9.5 shows
the outcome of some of this work.
Figure 9.2 shows the relationship between NO level and fuel
J±
consumption for a typical present rotary-engine powered vehicle and
similar stratified-charge rotary-engine vehicles. Although a
significant fuel-consumption improvement is made using the
stratified-charge principles, the basic relationship between NO
3C
level and fuel consumption holds. Whenever lower NO levels are
approached, the driveability is seriously impaired even with the
stratified-charge systems.
Although the stratified-charge work has shown promising results,
it is still in the early stages of development. Also, some type of
external clean-up device (i.e., thermal reactor, catalyst, etc.) is
still needed to achieve the emissions standards although the bare-
-------
94
TABLE 9.2
Typical Deterioration Factors of
Thermal Reactor-Eqiiijjpeji jlotary Engines
Pollutant Deterioration Factor
HC 1.0 - 1.05
CO L.O - 1.03
HO 1.02-1.05
x
-------
TABLE 9.3
Emissions Summary
System
Tail Pipe
HC CO NOx
Base Engine
HC CO NOx
EPA
MEG
350 V-8 -- 260 Cu. In, U'Floor
f f\
Bead Converter
0,29 1,88 2,3
2.7 8.4 2.3
GMRE -- 260 Cu. In. U'Floor
f T-\
Bead Converter
0.60 1.2 2.6
10.9 8.1 2.4
15.0/15.5
GM RE, U'Floor & Warm-Up Conv.
GM RE, Reactor/Conv. System
0,30 4.6 1.5
0.40 2.5 2.1
10.7 21.5 1.3
3.3 14.5 2.1
15,0/15.5
14.3
GM RE, Reactor Only
0,46 6.6 1.7
1 - low mileage
2 - 4,000 Ib weight class
3 - 3,500 Ib weight class
4 - Base engine values were measured at the reactor outlet
12.4
REF. 63 , 64
-------
TABLE 9.4
Rotary with Lean Reactor
Emission Target Actual Emissions Fuel Economy No. of
(HC, CO, NO , g/mi) (CO, HC, NO , g/mi) mpg Tests
No EGR 0.9/9/2.0 4.8/0.38/1.7 17.0
No EGR 0.41/3,4/2,0 2,0/0.18/1.? 16.4
EG! 2,4/0.21/0.85 15,3
EGR 2,3/0,27/0.74 15.1
I.¥. = 3,000 Ibs,
Manual Transmission
Engine displacement 80 C.I.D.
REF. 62
-------
97
TABLE 9.5
Emission and Fuel Consumption Characteristics of an
Experimental Open-Chamber Stratified-Charge Rotary Engine
EGR (%) 0 7-8% 20V
HC (g/mi) 0.24 0.22
CO (g/mi) 1.8 2.5
NO (g/mi) L.5 0.91 0.4
x
Fuel Consumption (ropg) 17.5 L6.8 14.0
* Bench data only
REF. 64
-------
2.0
_ 1.5
1,0
0.5
98
• Present System (1973-1974 Mazda)
• Open-Chamber Stratified Chsrge-j
A Divided-Chamber Stratified Chgrge-j
18 17 16 15 14 13 12
FUEL CONSUMPTION (mpg)
11
FIGURE 9.2 Comparison of NOX and Fuel Consumption
Characteristics of Various Rotary Engine Concepts.
10
Source: References 62, 63
-------
99
engine emissions are undoubtedly lower. It is doubtful if a fully
developed stratified-charge rotary-engine could be available before
the early to middle 1980fs.
9.4 Summary
Most of the rotary-engine effort to date has been concentrated
on improving durability and fuel consumption. Little effort has
been spent on understanding the basic combustion process or lowering
the bare-engine emissions. Most manufacturers appear to be looking
at the rotary engine for its packaging, performance and potential
cost advantages rather than as a solution to the emissions problem.
It appears that rotary-engine systems can meet near-term emissions
standards with reasonable fuel consumption. Although the advanced
stratified-charge rotary-engine concepts appear promising, it is
doubtful whether they can be available until the 1980's.
-------
10, STEATIFIED-CHARGE ENGINES
10.1 Introduction and General Background
a. General — The term "stratified-charge engine" has been
used for many years in connection with a variety of unconventional
engine combustion systems. Common to nearly all such systems is
the combustion of F/A mixtures having a significant gradation or
stratification in fuel concentration within the engine combustion
chamber. Hence the term "stratified charge." Historically, the
objective of stratified-charge-engine designs has been to permit
spark-ignition-engine operation with average or overall F/A. ratios
lean, beyond the ignition limits of conventional combustion systems.
The advantages of this type of operation will be enumerated shortly.
Attempts at achieving this objective date back to the first or
second decade of this century,
More recently, the stratified-charge engine has been
recognized as a potential means for control of vehicle pollutant
emissions with minimum loss of fuel economy. As a consequence, the
various stratified-charge concepts have been the focus of renewed
interest.
b. Advantages and disadvantages o_£_ lean-mixture operation —
Fuel-lean combustion as achieved in a number of the stratified-charge-
engine designs receiving current attention has both advantages and
disadvantages when considered from the combined standpoints of
emissions control, vehicle performance and fuel economy.
Advantages of lean mixture operation include the following:
Excess oxygen contained in lean-mixture combustion gases help
to promote complete oxidation of hydrocarbons (HC) and carbon
monoxide (CO) both in the engine cylinder and in the exhaust
system.
100
-------
101
, Lean-mixture combustion results in reduced peak engine-cycle
temperatures and can, therefore, yield lowered nitrogen oxide
(NO ) emissions.
x
Thermodynamic properties of lean-mixture-eombustion products
are favorable from the standpoint of engine-cycle thermal
efficiency (reduced extent of dissociation and higher effective
specific heats ratio),
Lean-mixture operation can reduce or eliminate the need for air
throttling as a means of engine load control. The consequent
reduction in pumping losses can result in significantly
improved part-load fuel economy.
Disadvantages of lean mixture operation include the
following:
* Relatively low-combustion gas temperatures during the engine
cycle expansion and exhaust processes can result from extreme-
ly lean operation. As a consequence, HC oxidation reactions are
retarded and unburned HC exhaust emissions can be excessive,
Engine modifications aimed at raising exhaust temperatures for
improved HC emissions control (retarded ignition timing, lowered
compression ratio, protracted combustion) necessarily impair
engine fuel economy.
If lean-mixture operation is to be maintained over the entire
engine load range, maximum power output and, hence, vehicle
performance are significantly impaired.
Lean-mixture exhaust gases are not amenable to treatment by
existing reducing catalysts for NO emissions control.
"
-------
102
Lean-mixture combustion, if not carefully controlled, can
result in formation of undesirable odorant materials that appear
in significant concentrations in the engine exhaust. Diesel
exhaust odor is typical of this problem and is thought to derive
from lean-mixture regions of the combustion chamber,
Measures required for control of NO emissions to low levels
(for example, EGR) can accentuate the above HC and odorant
emissions problems.
Successful development of the several stratified-charge-
engine designs now receiving serious attention will depend very much
on the balance that can be achieved among the foregoing favorable
and unfavorable features of lean combustion. This balance will, of
course, depend ultimately on. the standards or goals that are set for
emissions control, fuel economy, vehicle performance and cost. Of
particular importance are the relationships between three factors--
unburned hydrocarbon (UBHC) emissions,, NO emissions, and fuel
rf»
economy.
e. Stratifled-.charge-eng ine concepts — Charge stratification
permitting lean-mixture operation has been achieved in a number of
ways using differing concepts and design configurations.
Irrespective of the means used for achieving charge
stratification, two distinct types of combustion processes can be
identified. One approach involves ignition of a small and localized
quantity of flammable mixture which, in turn, serves to ignite a
much larger quantity of adjoining or surrounding fuel-lean-mixture—
too lean for ignition under normal circumstances. Requisite mixture
stratification has been achieved in several different ways ranging
from use of fuel injection directly into "open" combustion chambers
to use of dual combustion chambers divided physically into rich and
lean-mixture regions. Under most operating conditions, the overall
-------
103
or average P/A ratio is fuel-lean and the advantages enumerated above
for lean operation can be realized,
A second approach involves timed staging of the combustion
process. An initial rich-mixture stage in which major combustion
reactions are completed is followed by rapid mixing of rich-mixture
combustion products with an excess of air. Mixing and the resultant
temperature reduction can, in principle, occur so rapidly that
minimum opportunity for NO formation exists and, as a consequence,
NO emissions are low. Sufficient excess air is made available to
x
encourage complete oxidation of HC and CO in the engine cylinder and
exhaust system. The staged combustion concept has been specifically
exploited in divided-chamber or large-volume prechamber engine
designs. But it will be seen that staging is also inherent to some
degree in other types of stratified-eharge engines.
The foregoing would indicate that stratified-charge engines
can be categorized either as "lean-burn" engines or "staged-combustion"
engines. In reality, the division between concepts is not so clear
cut. Many engines encompass features of both concepts.
d. Scope -- During the past several years, a large number of
engine designs falling into the broad category of stratified-charge
engines have been proposed. Many of these have been evaluated by
competent organizations and have been found lacing in one or more
important areas, A much smaller number of stratificd-charge engine
designs have shoxm promise for improved emissions control and fuel
economy with acceptable performance, durability and production
feasibility. These are currently receiving intensive research
and/or development efforts by major organizations — both domestic
and foreign.
The purpose of this Consultant Report is not to enumerate
and describe the many variations of stratified-charge engine design
that have been proposed in recent years. Rather, it is intended to
-------
104
focus on those engines that are receiving serious development efforts
and for which a reasonably large and sound body of experimental data
has evolved. It is hoped that this approach will lead to a reliable
appraisal of the potential for stratlfied-charge engine systems.
10.2 Open-Chamber., Stratified-Charge Engines
a. General -- From the standpoint of mechanical design,
stratified-charge engines can be conveniently divided into two types:
open-chamber and dual-chamber. The open-chamber, stratified-charge
engine has a long history of research interest. Those engines
reaching the most advanced stages of development are probably the
Ford-programmed combustion process (PROCO) J and Texaco's
controlled combustion process (TCCS), ' Both engines employ a
combination of inlet air swirl and direct timed combustion-chamber
fuel injection to achieve a local fuel-rich ignitable mixture near
the point of ignition. For both engines, the overall mixture ratio
under most operating conditions is fuel lean,
Aside from these general design features that are common to
the two engines, details of their respective engine-cycle processes
are quite different, and these differences affect engine performance
and emissions characteristics,
b. The Ford PROCO engine
(1) Descriptions -- The Ford PROCO engine is an outgrowth
of a stratified-charge development program initiated by Ford in the
late 1950's. The development objective at that time was an engine
having diesel-like fuel economy but with performance, noise levels,
and driveability comparable to that of conventional engines. In the
1960's, objectives were broadened to include exhaust-emissions
control.
-------
105
A recent developmental version of the PROGO engine
is shown in Figure 10-1. Fuel is injected directly into the
combustion chamber during the compression stroke resulting in
vaporization and formation of a rich mixture cloud or kernel in the
immediate vicinity of the spark plug(s). A flame initiated in this
rich-mixture region propagates outwardly Co the increasingly fuel-
lean regions of the chamber. At the time, high air-swirl
velocities resulting from special orientation of the air inlet system
help to promote rapid mixing of fuel-rich combustion products with
excess air contained in the lean region. Air swirl is augmented by
the "squish" action of the piston as it approaches the combustion-
chamber roof at the end of the compression stroke. The effect of
rapid mixing can be viewed as promoting a second stage of combustion
in which rich mixture-zone products mix with air contained in lean
regions. Charge stratification permits operation with very lean F/A
mixtures with attendant fuel economy and emissions advantages. In
addition, charge stratification and direct fuel injection permit use
of high compression ratios with, gasolines of moderate octane quality -
again giving a substantial fuel economy advantage.
Present engine operation includes enrichment under
maximum power-demand conditions to mixture ratios richer than
stoicMometrie. Performance, therefore, closely matches that of
conventionally powered vehicles.
Nearly all PROCO development plans at the present time
include use of oxidizing catalysts for HC emissions control. For a
given HC emissions standard, oxidizing catalysts permit use of leaner
A/F ratios (lower exhaust temperatures) together with fuel injection
and ignition timing characteristics optimized for improved fuel
economy.
(2) Emissions and fuel economy -- Figure 10-2 is a plot
of P10CO vehicle fuel economy versus NO emissions based on the
-------
106
Fuel Injector
Spark Plug
FIGURE 10.I Ford PRQCO Engine.
Source: Reference 71
-------
15 (—
14 —
i-i--^:>":-l:i;!:\-^i--'>^;:':!;:: NOX vs- Fuel Economy with
•;'";-::::S::V'v:-^';::-:":fe No HC Restriction
HC Excessive
Q.
E
~ 13
o
LO
>
LJ
j>
o 12
o
LU
_(
LU
£ 11
10
/^" W/EGR >
— Approx. 1 jS
Correct * .S
to } 4 S
5000 Ib 1 f jS
T7S
S
—
1974 Pr
Ecorsorn
I II
HC-1.4
CO-7,1
Catalyst Feed
HC- 1.7
CO-12,7
Catalyst Feed
351 CIO, 5000 Ib inertia Weight
"100 C1D, 5000 Ib Inertia Weight
351 CID, 4 500 Ib Inertia Weight
19/4 Production Average Fuel
4500 Ib :
!•>:•:•:•>:•:-:-:-:-:-:•:•:•:•:•:•:•:•:•:•:•:•:•:-:•
;•.•:•:•:-.•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:
1 1
:•,-,', •,',•,'.•,'.•.-.-,-.•.-.-.•.:
v-:-;-;:-:-:-;-:-:-:-:-:-:-:-:-:-:
0 1.0 2,0
NOx EMISSIONS, CVS CH {g/mi)
FIGURE 10.2 Ford PROCO Engine Fuel Economy and Emissions.
3.0
Source: References 70, 71
-------
108
Federal CVS-CH test procedure. Also included are corresponding HC
and CO emissions levels. Only the most recent test daCa have been
plotted since these are most representative of current program
directions and also reflect most accurately current emphasis on
improved vehicle fuel economy. ' For purposes of comparison,
average fuel economies for 1974 production vehicles weighing 4,500
72
pounds and 5,000 pounds have been plotted. (The CVS-C values
reported in Reference 72 have been adjusted by 57, to obtain estimated
CVS-CH values.)
Data points to the left on Figure 10-2 at the 0.4 g/mi
NO level represent efforts to achieve statutory 1977 emissions
X 70
levels. While the NO target of 0.4 g/mi was met, the requisite
x
use of EGR resulted in HC emissions above the statutory level.
A redefined NO target of 2.0 g/mi has resulted in
x
the recent data points appearing in the upper right-hand region of
Figure 10-2. The HC and CO emissions values listed are without
exhaust oxidation catalysts. Assuming catalyst conversion
efficiencies of 50%-607o at the end of 50,000 miles of operation, HC
and CO levels will approach but not meet statutory levels. At the
indicated levels of emissions-control fuel economy is improved some
40% to 45% relative to 1974 production-vehicle averages for the same
weight class.
The cross-hatched, horizontal band appearing across
the upper part of Figure 10-2 represents the reductions in NO
emissions achievable with use of EGR is HC emissions are unrestricted.
The statutory 0,4 g/mi Level can apparently be achieved with this
engine with little or no loss of fuel economy but with significant
increases in HC emissions. The HC increase is ascribed to the
quenching effect of EGR in lean-mixture regions of the combustion
chamber.
-------
109
(3) Fuel requirements — Current P10CO engines operated
with 11:1 compression ratio yield a significant fuel economy
advantage over conventional production engines at current compression
ratios. According to Ford engineers, Che PROCO engine at this
compression ratio is satisfied by typical full-boiling commercial
gasolines of 91 RON rating. Conventional engines are limited to
compression ratios of about 8:1 and possibly less for operation on
similar fuels.
Results of preliminary experiments indicate that the
PROCO engine may be less sensitive to fuel volatility than conventional
engines--an important factor in flexibility from the standpoint of
the fuel supplier.
(4) Present status -- Present development objectives are
two-fold:
Develop calibrations for alternate emissions target levels
to determine the fuel economy potential associated with
each level of emissions control.
Convert engine and auxiliary systems to designs feasible
for high-volume production,
c. The Texaco TCCja _s^tratif ied_~_char£e engine
(1) General description -- Like the Ford PROCO engine,
Texaco's TCCS system involves coordinated air swirl and direct
combostion-chamber; fuel injection to achieve charge stratification.
Inlet-port-induced cylinder air swirl rates typically approach ten
times the rotational engine speed, A sectional view of the TCCS
combustion chamber is shown in Figure 10-3.
Unlike the PROCO engine, fuel injection in the TCCS
engine begins very late in the compression stroke -- just before the
desired time of ignition. As shown in Figure 10-4, the first portion
-------
Piston
— Shrouded intake Valve
— Fuel Nozzie
Cylinder Head
Cylinder Block
Fuel Nozzle
Intake
Port
Exhaust
Port
Horizontal Projections of Nozzle
and Spark Plug Centerlines
FIGURE L0.3 Texaco TCCS Engine,
Source: Reference 73
-------
Ill
Nozzle
Spark Plug
1 - Fuel Spray
2 - Fuel-Air Mixing Zone
3 - Flame Front Area
4 - Combustion Products
FIGURE 10.4 Texaco Controlled Combustion System,
Source: Reference 73
-------
112
of fuel injected is Immediately swept by the swirling air into the
spark plug region where ignition occurs and a flame front is
established. The continuing stream of injected fuel mixes with
swirling air and is swept into the flame region. In many respects,
the Texaco process resembles the spray burning typical of diesel
combustion with the difference that ignition is achieved by energy
from an electric spark rather than by high compression temperatures,
The Texaco engine, like the diesel engine, does not have a significant
fuel octane requirement. Further, use of positive spark ignition
obviates fuel cetane requirements characteristic of diesel engines.
The resultant flexibility of the TCCS engine regarding fuel
requirements is a significant attribute.
In contrast to the TCCS system, Ford's PROCO system
employs relatively early injection, vaporization, and mixing of fuel
with air. The combustion process more closely resembles the
premixed flame propagation typical of conventional gasoline engines.
The PROCO engine, therefore, has a definite fuel octane requirements
and cannot be considered a multifuel system,
The TCCS engine operates with high compression ratios
and with little or no inlet air throttling except at idle conditions.
As a consequence, fuel economy is excellent—both at full load and
under part-load operating conditions,
(2) Exhaust emissions and fuel economy -- Low exhaust
temperatures characteristic of the TCCS system have necessitated use
of exhaust oxidation catalysts for control of HC emissions to low
levels. All recent development programs have, therefore, included
use of exhaust oxidation catalysts, and most of the data reported
here represent tests with catalysts installed or with engines tuned
for use with catalysts.
Figures 10-5 and 10-6 present fuel economy data at
several exhaust emissions levels for two vehicles--a U.S. Army M-151
-------
25 —
Maximum Economy Setting
141 CID, 10:1 CR
2500 Ib inertia Weight
1.07 HC
0,84 CO
O5
Q.
I
u
o
24
23 —
^
o
^
S 22
LLJ
A
— Retard •+
EGR
0.51 HC
0.64 CO
j
X
5-8
Retard
0,73 HC
1,2 CO
0,61 HC
0.85 CO
Retard •+ EBP
21
20 —
0,36 HC
^ 1.15 CO
Retard + EBP + EGR
0.4 0,6 0,8 1-0 1.2 1,4
NOX EMISSIONS, CVS-CH (g/mi)
FIGURE 10.5 Texaco TCCS Powered Cricket Vehicle.
1.6
2,0
Source: Reference 73
-------
25
en
O.
E.
o
>
o
>
s
o
o
o
LU
_t
I—
D
20
15 —
141 CID, 10:1 CR
2750 Ib Inertia Weight
^k HC—3 1
Maximum Economy Adjustment CO-7.0 Catal¥st Feed
8 Retard
A HC--3.2
Catalyst Feed
Low EGR
Medium EGR
HC-3.6
CO-6.7
Catalyst Feed
HC-0.33
CO-1.05
HC-0.35
4 CO-1.41
13° Retard
High EGR
5 Retard
HC-0.30
1974 Production
Average Fuel Economy
(2750 Ib)
0.4
1.0
2.0
NOX EMISSIONS, CVS-CH (g/mi)
FIGURE 10,6 Turbocharged Texaco TCCS, M151 Vehicle.
Source: Reference 73
-------
115
vehicle with naturally aspirated 4-cylinder TCCS conversion, and a
73 74
Plymouth Cricket with turbocharged 4-cylinder TCCS engine. '
Turbocharging has been used to advantage to increase maximum power
output. Also plotted in these figures are average fuel economies
72
for 1974 production vehicles of similar weight.
When optimized for maximum fuel economy, the TCCS
vehicles can meet NO levels of about 2.0 g/mi. It should be noted
x
that these are relatively lightweight vehicles and that increasing
vehicle weight to the 4,000-5,000-pound level could result in
significantly increased NO emissions. Figures 10-5 and 10-6 both
jC
show that engine modifications for reduced NO levels including
X
retarded combustion timing, EGR and increased exhaust back pressure
result in substantial fuel economy penalties.
For the naturally aspirated engine, reducing NO
X
emissions from the 2,0 g/mi level to 0.4 g/mi incurred a fuel
economy penalty of 20%,. Reducing NO from the turbocharged engine
it
from 1,5 g/mi to 0,4 g/mi gave a 25% fuel economy penalty. Fuel
economies for both engines appear to decrease uniformly as NO
X
emissions are lowered.
For the current TCCS systems, most of the fuel
economy penalty associated with emissions control can be ascribed
to control of NO emissions, although several of the measures used
x
for NO control (retarded combustion timing and increased exhaust
X
back pressure) also help to reduce HC emissions, HC and CO emissions
are effectively controlled with oxidation catalysts resulting in
relatively minor reductions in engine efficiency.
(3) TCCS fuel requirements — The TCCS engine is unique
among stratified-charge systems in its multifuel capability.
Successful operation with a number of fuels ranging from gasoline
to No, 2 diesel has been demonstrated. Table 10-1 lists emissions
levels and fuel economies obtained with a turbocharged TCCS-powered
-------
116
74
M-151 vehicle when operated on each of four different fuels.
These fuel encompass wide ranges in gravity, volatility, octane
number and cetane level as shown in Table 10-2,
TABLE 10-1
Emissions and Fuel Economy of Turbocharged
TGCS Engine-Powered Vehicle
Emissions
Fuel
Gasoline
JP-4
100-600
Wo. 2 Diesel
EC
0.33
0.26
0.14
0.27
E/mi2
CO
1.04
1.09
0.72
1.14
NO
X
0.61
0.50
0.59
0.60
Fuel Economy
2
mpg
19.7
20.2
21.3
23.0
vehicle, 8 degrees combustion retard, 16% light
load EGRS two catalysts.
"TVS-CH, 2, 750 pounds inertia weight.
REP. 74
-------
117
TABLE 10-2
Fuel Specifications for
TCCS Emission Tests
Gasoline
Gravity, °API 58,8
Sulfur, %
Distillation, F
IBP 86
10% 124
50% 233
90% 342
EP 388
TEL, g/gal. 0.002
Research Octane 91.2
Cetane Wo.
100-600
48.6
0.12
110
170
358
544
615
0.002
57
35.6
JP-4
54.1
0.020
136
230
314
459
505
-
-
-
No. 2
Diesel
36.9
0,065
390
435
508
562
594
-
-
48.9 REF. 74
Generally^ the emissions levels were little affected by the wide
variations in fuel properties. Vehicle fuel economy varied in
proportion to fuel energy content.
As stated above, the TCCS engine is unique in its
multifuel capability. The results of Tables 10-1 and 10-2 demonstrate
that the engine has neither significant fuel octane nor cetane
requirements and, further, that it can tolerate wide variations in
fuel volatility. The flexibility offered by this type of system
could be of major importance in future years.
-------
118
(4) Durability, performance, production readiness —
Emissions-control-system durability has been demonstrated by mileage
accumulation tests. Ignition-system service is more severe than for
conventional engines due to heterogeneity of the F/A mixture and also
to the high compression ratios involved. The ignition system has
been the subject of intensive development and significant progress in
system reliability has been made,
A preproduction, prototype engine employing the TCCS
process is now being developed by the Hercules Division of White
Motors Corporation, under contract to the U.S. Army Tank Automotive
Command, Southwest Research Institute will conduct reliability
tests on the White-developed engines when installed in military
vehicles,
10.3 Small Volume Prechamber Engines (3-Valve. ,.Pr_e; chamber; jSngines,
Jet Ignition Enginesa Torch Ignition_Engines)
a. General — A number of designs achieve charge stratification
through division of the combustion region into two adjacent chambers.
The emissions reduction potential for two types of dual-chamber
engines has been demonstrated. First, in a design traditionally
called the "preehamber engine," a small auxiliary or ignition chamber
equipped with a spark plug communicates with the much larger main
combustion chamber located in the space above the piston (Figure 10-7).
The prechamber, which typically contains 5%-15% of the total
combustion volume, is supplied with a small quantity of fuel-rich
ignitable F/A mixture while a large quantity of very lean and
normally unignitable mixture is applied to the main chamber above
the piston. Expansion of high-temperature flame products from the
prechamber leads to ignition and burning of the lean main chamber
F/A charge. Ignition and combustion in the lean, main-chamber region
are promoted both by the high temperatures of prechamber gases and by
-------
119
intake
Prechamber
(Fuei-Rich Mixture)
Spark P!ug
Intake
Exhaust
Main Chamber
(Fuel-Lean Mixture)
FIGURE 10.7 3-Valve Prechamber Engine Concept.
-------
120
the mixing that accompanies the jet-like motion of prechamber products
into the main chamber.
Operation with lean overall mixtures tend to limit peak
combustion temperatures, thus minimizing the formation of nitric
oxide. Further, lean-mixture combustion products contain sufficient
oxygen for complete oxidation of HC and CO in the engine cylinder
and exhaust system.
It should be reemphasized here that a traditional problem.
with lean mixture engines has been low exhaust temperatures which
tend to quench HC oxidation reactions Leading to excessive emissions.
Control of HC emissions to low levels requires a retarded
or slowly developing combustion process. The consequent extension
of heat release into late portions of the engine cycle tends to raise
exhaust gas temperatures, thus promoting complete oxidation of HC
and CO.
b. Historical background and current status
(1) Early development objectives and engine designs — The
prechamber, stratified-charge engine has existed in various forms
for many years. Early work by Ricardo indicated that the engine
could perform very efficiently within a limited range of carefully
controlled operating conditions. Both fuel-injected and carbureted
prechamber engines have been built. A fuel-injected design
initially conceived by Brodersen was the subject of extensive
study at the University of Rochester for nearly a decade, *
Unfortunately, the University of Rochester work was undertaken
prior to widespread recognition of the automobile emissions problem,
and, as a consequence, emissions characteristics of the Brodersen
engine were not determined. Another prechamber engine receiving
7 R
attention in the early 1960's is that conceived by R. M. Heintz.
The objectives of this design were reduced HC emissions, increased
-------
121
fuel economy and more flexible fuel requirements,
Experiments with a prechamber engine design called
79
"the torch-ignition engine" were reported in the U.S.S.R, by Nilov
ori
and later by Kerimov and Mekhtier, This designation refers to the
torch-like jet of hot combustion gases issuing from the precoinbustion
81
chamber upon ignition. In a recent publication., Varshaoski et _al.
have presented emissions data obtained with a torch-ignition engine,
These data show significant pollutant reductions relative to
conventional engines; however, their interpretation in terms of
requirements based on the U.S. emissions test procedure is not clear,
(2) Current developments -- A carbureted three-valve,
prechamber engine, the Honda CVCC system, has received considerable
82
recent attention as a potential low-emissions power plant. This
system is illustrated in Figure 10-8. Honda's current design
employs a conventional engine block and piston assembly. Only the
cylinder head and fuel inlet system differ from current automotive
practice. Each cylinder is equipped with a small precombustion
chamber communicating by means of an orifice with the main combustion
chamber situated above the piston, A small inlet valve is located
in each prechamber. Larger inlet and exhaust valves typical of
conventional automotive practice are located in the main combustion
chamber. Proper proportioning of F/A mixture between prechamber
and main chamber is achieved by a combination of throttle control
and appropriate inlet valve timing, A relatively slow and uniform
burning process giving rise to elevated combustion temperatures late
in the expansion stroke and during the exhaust process is achieved.
High temperatures in this part of the engine cycle are necessary
to promote complete oxidation of HC and CO. It should be noted that
these elevated exhaust temperatures are necessarily obtained at the
expense of a fuel economy penalty.
-------
122
FIGURE 10.8 Honda CVCC Engine.
Source: Reference 86
-------
123
To reduce HC and CO emissions to required levels, it
has been necessary for Honda to employ specially designed inlet and
exhaust systems. Supply of extremely rich F/A mixtures to the
precombustion chambers requires extensive inlet manifold heating to
provide adequate fuel vaporization. This is accomplished with a heat
exchange system between inlet and exhaust streams.
To promote maximum oxidation of HC and CO in the lean
mixture CVCC engine exhaust gases, it has been necessary to conserve
as much exhaust heat as possible and also to increase exhaust
manifold residence time. This has been done by using a relatively
large exhaust manifold fitted with an internal heat shield or liner
to minimize heat losses. In addition} the exhaust ports are
equipped with thin metallic liners to minimize loss of heat from
exhaust gases to the cylinder heat casting.
Engines similar in concept to the Honda CVCC system
are under development by other companies including Toyota and Nissan
in Japan and General Motors and Ford in the United States.
Honda presently markets a CVCC-powered vehicle in
Japan and plans U.S. introduction in 1975. Other manufacturers,
including General Motors and Ford in the U.S., hafe stated that
CVCC-type engines could be manufactured for use in limited numbers
of vehicles by as early as 1977 or 1978.
c. Emissions gnd fjjel economy with CVCC-type engines
(1) Recent emissions test results — Results of emissions
tests with the Honda engine have been very promising. The emissions
levels shown in Table 10-3 are typical and demonstrate that the
Honda engine can meet statutory HC and CO standards and can approach
Q O
the statutory NO standard. Of particular importance, durability
X.
of this system appears excellent as evidenced by the high mileage
emissions levels reported in Table 10-3. A.ny deterioration of
-------
124
emissions after 50,000 miles of engine operation was slight
and apparently insignificant.
TABLE 10-3
Honda Compound Vortex-Controlled
Combustion-Powered Vehicle Emissions
Fuel Economy,
Emissions3 mpg
g/mi 1975 1972
HC CO NO FTP FTP
x
Low Mileage Car3 No. 3652 0,18 2.12 0.89 22.1 21.0
50,000-Mile Car No. 2034 0.24 1.75 0,65 21.3 19-8
1976 Standards 0.41 3,4 2.0
1977 Standards 0.41 3.4 0.4
Honda Civic vehicles,
21975 CVS XH procedure with 2000-lb inertia weight.
3
Average of five tests,
4
Average of four tests,
I ____ . REF. 83
Recently, the EPA has tested a larger vehicle
84
converted to the Honda system. This vehicle, a 1973 Chevrolet
Impala with a 300-CID V-8 engine, was equipped with cylinder heads
and an induction system built by Honda. The vehicle met the 1976
interim federal emissions standards though NO levels were
A!
substantially higher than for the much lighter-weight Honda Civic
vehicles.
-------
125
Results of development tests conducted by General
g c
Motors are shown in Table 10-4. These tests involved a 5,000 Ib
Chevrolet Impala with stratified-charge engine conversion. EC and CO
emissions were below 1977 statutory limits, while NO emissions
X
ranged from 1.5 to 2.0 g/mi. Average CVS-CH fuel economy was 11.2
miles per gallon.
10-4
Emissions and Fuel Economy for
Chevrolet Impala Stratified-
Charge Engine Conversion
Test
1
2
3
4
5
Average
Exhaust
Emissions }
g/mi
HC
0.20
0,26
0.20
0.29
0.18
0.23
CO
2.5
2,9
3.1
3,2
2.8
2.9
NO
X
1.7
1,5
1.9
1.6
1.9
1.7
Fuel
Economy,
rapg
10.8
11.7
11.4
10.9
11.1
11.2
1CVS-CH, 5,000-lb inertia weight.
REF. 85
(2) HC control has a significant impact on fuel economy --
In Figure 10-9, fuel economy data for several levels of HC emissions
from CVCC-type stratified-charge engines are plotted. ' At the
1.0 g/mi HC level, stratified-charge engine fuel economy appears
-------
28
26
a.
_§
O 24
u
O
O
UJ
_i
LJJ
D
Uu
22
20
18 —
NO -1.2
1.5 liter
NO -0.9
2 liter
2750 Ib
* HONDA CVCC-2000 Ib
O DATSUN NVCC
2500 Ibs
NO -1.5
0,2 0,4 0.6
HYDROCARBON EMISSIONS, CVS-CH
0.8
1.0
FIGURE 10.9 Fuel Economy Versus HC Emissions for 3-Valve Prechamber Engines.
Source: References 86, 87
-------
127
better than the average fuel economy for 1973-74 production vehicles
of equivalent weight. Reduction of HC emissions below the 1,0 g/mi
level necessitates lowered compression ratios and/or retarded ignition
timing with a consequent loss of efficiency. For the lightweight
(2,000-lb) vehicles, the 0.4 g/mi RC emissions standard can be met with
a fuel economy of 25 mpg, a level approximately equal to the average
7?
of 1973 production vehicles in this weight class. *~ For heavier cars,
the HG emissions versus fuel economy trade-off appears less favorable.
A fuel economy penalty of 107* relative to 1974 production vehicles in
the 2,750-lb weight class is required to meet the statutory 0.4 g/mi
HC level.
(3) Effect of HO emissions control on fuel economy -- Data
X " 86
showing the effect of NO emissions control appear in Figure 10-10.
3C
These data are based on modifications of a Honda C,VCC-powered Civic
vehicle (2,000-lb test weight) to meet increasingly stringent NO
standards ranging from 1,2 g/mi to as low as 0.3 g/mi. For all tests,
HC and GO emissions are within the statutory 1977 standards.
NO control as shown in Figure 10-10 has been effected
x
by use of EGR. in combination with retarded ignition timing. It is
clear that control of NO emissions to levels below 1,0 to 1.5 g/mi
x
results in significant fuel economy penalties. The penalty increases
uniformly as NO emissions are reduced and appears to be 25% or more
j\.
as the 0.4 g/mi NO level is approached.
It should be emphasized that the data of Figure 10-10
apply specifically to a 2,000-lb vehicle. With increased vehicle
weight, NO emissions control becomes more difficult and the fuel
yi
economy penalty more severe. The effect of vehicle weight on NO
emissions is apparent when comparing the data of Table 10-3 for 2,000-
lb vehicles with that of Table 10-4 for a 5,000-Ib vehicle. While HC
and CO emissions for the two vehicles are roughtly comparable, there
is over a factor of two difference in average NO emissions.
-------
26
r
oi 24
CL
I
o
CO
o
O
2
o
o
LU
_l
UJ
D
LL
22
20
18
128
HC-0.23
CO-2.2
O
o
HC-0.17
CO-2.3
/
O HC-0.33
CO-3.0
O
HC^O,2
CO-2,7
0.2
0,4
0.6
0.8
1.0
1.2
NOV EMISSIONS, CVS-CH (g/mi)
/\
FIGURE 10,10 Fuel Economy Versus NOX Emissions for Honda CVCC Powered
Vehicles.
Source: Eeferen.ee 86
-------
129
d. Fuel requirements -- To meet present and future U.S.
emissions-control standards, compression ratio and maximum ignition
advance are limited by HC emissions control rather than by the octane
quality of existing gasolines. CVCC engines tuned to meet 1975
California emissions standards appear to be easily satisfied with
presently available 91 RON commercial unleaded gasolines.
CVCC engines are lead-tolerant and have completed emissions
certification test programs using leaded gasolines. However, with
the low octane requirement of the CVCC engine as noted above, the
economic benefits of lead antiknock compounds are not realized.
It is possible that fuel volatility characteristics may be
of importance in relation to vaporization within the high-temperature,
fuel-rich regions of the prechamber cup, inlet port and prechamber
inlet manifold. However, experimental data on this question do not
appear to be available at present.
10.4 Pi videcl--_Ch amber Staged Combustion.Engines (Large-Volume
Prechamber Engines, Fuel-Injected Blind Prechamber Engines)
a. General — Dual-chamber engines of a type often called
"divided-chamber" or "large-volume prechamber" employ a two-stage
combustion process. Here initial rich-mixture combustion and heat
release (first stage of combustion) are followed by rapid dilution of
combustion products with relatively low-temperature air (second
state of combustion). The object of this engine design is to effect
the transition from overall rich combustion products to overall
lean products with sufficient speed that time is not available for
formation of significant quantities of NO. During the second low-
temperature, lean stage of combustion, oxidation of HC and CO goes
to completion.
An experimental divided-chamber engine design that has been
-------
130
87,88
built and tested is represented schematically in Figure 10-11.
A dividing orifice (3) separates the primary combustion chamber (1)
from the secondary combustion chamber (2), which includes the
cylinder volume above the piston top. A fuel injection (4) supplies
fuel to the primary chamber only.
Injection timing is arranged such that fuel continuously
mixes with air entering the primary chamber during the compression
stroke. At the end of compression, as the piston nears its top
center position, the primary chamber contains an ignitable F/A
mixture while the secondary chamber adjacent to the piston top
contains only air. Following ignition of the primary chamber mixture
by a spark plug (6) located near the dividing orifice, high-
temperature, rich-mixture combustion products expand rapidly into
and mix with the relatively cool air contained in the secondary
chamber. The resulting dilution of combustion products with attendant
temperature reduction rapidly suppresses formation of NO. At the
same time, the presence of excess air in the secondary chamber tends
to promote complete oxidation of HC and CO,
b. Exhaust emissions and fuel economy — Results of limited
research conducted both by university and industrial laboratories
indicate that NO reductions of as much as 80%-957» relative to
x
conventional engines are possible with the divided-chamber staged
combustion process. Typical experimentally determined NO emissions
89 x
levels are presented in Figure 10-12. Here NO emissions for two
X
different divided-chamber configurations are compared with typical
emissions levels for conventional uncontrolled automobile engines.
The volume ratio, g appearing as a parameter in Figure 10-12,
represents the fraction of total combustion volume contained in
the primary chamber. For g values approaching 0.5 or lower, NO
X
emissions reach extremely low levels. However, maximum power output
capability for a given engine size decreases with decreasing 6 values.
-------
131
Fuel Injector
FIGURE 10.11 Ford Divided Chamber.
Source: References 87,
-------
132
5000
E 4000
a
a
o
ac
co
LU
a
x
o
I
X
3000—
2000
1000
MBT Ignition Timing
Wide Open Throttle
Conventional
Chamber
Fraction of Total Combustion
Volume in Primary Chamber
Divided Chamber, $ - 0.85
Divided Chamber, {} = 0.52
0.5 0.6 0.7 0.8 0.9 1.0
OViRALL FUEL-AIR RATIO
1.1
FIGURE 10,12 Comparison of Conventional and
Divided Combustion Chamber NO Emissions.
x
Source: Reference 90
-------
133
Optimum primary chamber volume must ultimately represent a compromise
between low emissions levels and desired maximum power output,
KG, and particularly CO, emissions from the divided-chamber
engine are substantially lower than conventional engine levels,
However, further detailed work with combustion-chamber geometries
and fuel-injection systems will be necessary to fully evaluate
the potential for reduction of these emissions.
Recent tests by Ford Motor Company show that the large
volume prechamber engine may be capable of better HC emissions
control and fuel economy than their PROCO engine. This is shown
by the laboratory engine test comparison of Table 10- 5
.83
Engine
PROCO
Divided Chamber
PROCO
Divided Chamber
TABLE 10-5
Single-Cylinder Low Emissions
Engine Tests
NOX
Reduction
Method
EGR
None
EGR
None
Emissions,
g/1. hp-hr
NO
X
1.0
1.0
0.5
0,5
HC
3.0
0.4
4.0
0.75
CO
13.0
2.5
14.0
3.3
i
Fuel
EC o no ray s
lb/1, hp-hr
0.377
0.378
0,383
0.377 REF, 83
Fuel-injection-spray characteristics are critical to the
control of HC emissions from this type of engine, and Ford's success
in this regard is probably due in part to use of the already highly-
developed PROCO gasoline injection system. Figure 10-13 is a cutaway
view of Ford's adaptation of a 400-CID V-8 engine to the divided-
t, t, 90
chamber system.
-------
401 CIO
UJ
FIGUHS 10.13
Source: Reference 90
-------
135
Volkswagen (VW) has recently published results of a
91
program aimed at development of a large-volume prechamber engine.
In the VW adaptation, the primary chamber which comprises about 307,
of the total clearance volume is fueled by a direct, time injection
system, and auxiliary fuel for high-power output conditions is
supplied to the cylinder region by a carburetor.
Table 10- 6 presents emissions data for both air-cooled
92
and water-cooled versions of VW's divided-chamber engine. " Emissions
levels, while quite low, do not meet the ultimate 1978 statutory U.S.
standards.
TABLE 10-6
Volkswagen Large-Volume
Prechamber Engine Emissions
Engine
Exhaust
Emissions,
g/nii
HC
CO
NO,
Engine Specifications
1.6 Liter
Air-Cooled
2.0-Liter
Water-Cooled
CVS -CH
2.0
5.0
0.9
1.0
4,0
1.0
8,4:1 compression ratio, pre-
chamber 2870 of total
clearance volumes conventional
exhaust manifold, direct pre-
chamber fuel injection
9:1 compression ratio, prechamber
volume 281 of total clearance
volume, simple exhaust manifold
reactor? direct prechamber fuel
injection
REF. 92
-------
136
c. Problem Areas
A number of major problems inherent in the large volume
prechamber engine remain to be solved. These problems include the
following:
Fuel injection spray characteristics are critically important
to achieving acceptable HC emissions. The feasibility of
producing a satisfactory injection system has not been
es tablished.
Combustion noise due to high turbulence levels and, hence,
high rates of heat release and pressure rise in the
prechamber, can be excessive. It has been shown that the
noise level can. be modified through careful chamber design
and combustion event timing.
If the engine is operated with prechamber fuel injection as
the sole fuel source, maximum engine pox^er output is
limited. This might be overcome by auxiliary carburetion
of the air inlet for maximum power demand or possibly by
turbocharging. Either approach adds to system complexity.
The engine is characterized by low exhaust temperatures
typical of most lean mixture engines.
-------
11. DIESEL ENGINES
11.1 Introduction
Many techniques have been sought for reducing the harmful
emissions from passenger cars in an effort to clean the air. Exhaust-
emissions standards have been set by the federal government and the.
state of California for three species; hydrocarbon (HC), carbon
monoxide (CO) and nitrogen oxides (NO ). It is expected that other
5C
species which are equally or even more harmful than these will be
controlled in the future,
The regulated and nonregulated emissions from diesel-powered
cars are studied in this Section, The fuel economy and initial and
maintenance costs of the diesel are compared with the gasoline engine.
Finally, the intrinsic problem areas associated with the auto-ignition
process in the diesel engine are examined.
The approach taken in this Section is to compare the characteristics
of the diesel-powered cars with those of cars powered by regular
gasoline engines, stratified-charge engines, Wankel, or gas turbine
engines.
11.2 Regulated Emissions
93
a. General -- Table 11.1 and Figure 11.1 give a summary of tests
carried out by EPA-Ann Arbor, and recent results obtained from the
manufacturers. The Mercedes 220V and 240D and Datsun-Nissan 220C
have an inertia weight of 3,500 Ib, and the Peugeot 504D and Opel
Rekord 2100D have an inertia weight (I.W.)of 3,000 Ib. All of these
engines have four cylinders. The hydrocarbon emission from the
Peugeot 504D was 3.1 g/mi which is very high compared to all other
94
diesel-powered cars. Recent results by Southwest Research showed
that the Peugeot 504D produced 2,0 g/mi HC, Peugeot Inc. reported
at a meeting of foreign manufacturers held by the Committee on Motor
Vehicles Emissions May 21-23, 1974, that with modifications, their
137
-------
TABLE 11.1
Vehicle
Mercedes 220D
Mercedes 220D
(modified)
Mercedes 240D
Peugeot 504D
Peugeot 504D
(modified)
Datsun-Nissan 220C
(as received)
Datsun-Nissan 220C
(after 4,000 miles)
Opel Rekord 2100D
Pick-up Truck
Retrofit (Nissan
Diesel)
Mass Emissions and Fuel Economy
From Diesel Engines
(1975 Federal Test Procedure)
Inertia
No. of Tests Weight
5
5
3
5
3
3
3
3
,500
,500
,500
,000
Ib
Ib
Ib
Ib
Transmission
4
4
4
4
speed
speed
speed
speed
auto
auto
auto
manual
HC
(B/mi)
0.34
0.28
0.18
3.11
CO
(B/mi)
1.42
L.oe
1.0
3.42
KOX
(B/mi)
1.
1,
1.
1.
43
48
5
07
Fuel
Economy
(mpg)
23.6
24,6
23. 61
25.2
(Manufac turer's
Data) 3,000 Ib
2 3,500 Ib
4 speed manual
4 speed manual
0.40-0,60 1,1-1.6 1.3-L.5
0.38 1.69 1.72
24.0
2
4
3
3
,500
,000
Ib
Ib
4
3
speed
speed
manual
auto
0.23
0.40
1.34
1.16
1,
1.
36
34
28,1
23.8
Ul
00
4,500 Ib 4 speed manual
1.70
3.81
1.71
21.4
The fuel economy in this case is based on one measurement only.
REF 93
-------
139
3
1
X
O
z
1
20
_ 16
E
3 12
O
u
8
4
2
E
Q]
£ 1
(3-1! 1975-1976
12
1C
,
0) 1977
.41 1978
— (15! 1975-1976
—
—
(3,4) 1977-1978
i i i — i i — i i — i i — i r~i
r — i
i
^
r
(1.5) 1975-1976
1
1
-
(0-41) 19
n n m n
Q~t D"t:? D"t § 8 °s
fsi ^ ^J ^ **~ ^ ^ ^ ^ — ^*J *^
w ci ^cL'g ™ d r"I T "2
Ll^C/^ ^JC/}^ CQuj 3CJ Q- °k_
;>TT 5-rS. 5-* i3o°- ^H §>•£
77-1978
<0 CM W * rf 3 "
Q IN ^ CC 1 ^) ffi
a, Q-
FIGURE 1101 Emissions from Diesel Powered Cars (1975 FTP)
Source; Reference 94
-------
140
ear produces 0,6 g/tui HC»
Figure 11,1 shows that all of these diesel-powered cars,
except the Peugeot 504D? can meet the 1975-76 Federal, 1975-76
California, and 1977 Nationwide Standards for HC, CO and NO . Also,
J^
all these cars, except the Peugeot 504D, can meet the 1978 Nationwide
Standards for HC and CO, The problem with these diesel-powered cars
is in meeting the NO emissions standard of 0,40 g/tai in 1978.
x
Some HO controls have been applied to the diesel engine
x
and were found to affect the other emissions.
The control of NO emissions in diesel engines should be made
x
during the combustion process. Whereas gasoline engines can employ a
reduction catalyst * to control NO , such a technology is not
x
effective in diesel engines because of the low level of CO, and the
presence of a relatively high concentration of oxygen in the exhaust,
even under full-load conditions,
Reduction in NO formation during the combustion process is
achieved by reducing either the maximum temperature reached, the oxygen
97
concentration, or the residence time. This can be achieved by any
of the following methods or a combination of them.
b. Exhaust gas_ recirculation -- EGR (exhaust gas recirculation)
is an effective method for the reduction of NO emissions in diesel
x
as well as in many other types of combustion engines. It is believed
that its main effect is to reduce the maximum temperatures by
increasing the heat capacity of the charge,
98
Data reported by Daimler-Benz AG are given in Figure 11,2
for a speed of 2,400 rpm and two loads. Increasing EGR reduces NO
nfC
with little effect on HC and CO up to EGR values of 20%, where NO
' x
is reduced by about 20% at the low load and 30% at the higher load.
Increasing EGR above 20% results in an increase in HC and CO emissions,
The smoke starts to increase at 40% EGR at the light load and 20% EGR
-------
141
n = 2,400 mirf
SZ-BOSCH
3
1
p = 1.8 kp/cm2
—
n -- 2,400min '
pc = 3.6 kp/crn2
0.2
z>
_l
o
o
u
0.2
J
160
.
O
m
oc
a.
I B
80
40
120 i~
40
0
200 r—
E
o.
O 100 —
10
20 30
EGR {%)
40
10 20
EGR (%)
30
FIGURE 11.2 Effect of EGR on the Emissions from a Mercedes
Diesel Engine.
Source: Reference 98
-------
142
at the higher load. The Daimler-Benz results are for steady-state
conditions.
The effects of EGR on the emissions under the 1975 Federal
99
Test Procedure (FTP) are reported for an Opel Rekord diesel car,
and are shown in Figure 11.3. The increase in EGR increases both
HC and CO emissions above the 1977 standards, while NO is still above
5C
the 1978 standards of 0.4 g/mi. From this figure, it appears that
EGR is effective in reducing NO to about 1.0 g/mis while the HC and
5t
CO emissions are below the 1977 and 1978 standards of 0.41 and 3.4
g/tni, respectively.
Daimler-Benz reported that EGR does not affect power or
cause fuel penalty at part-load conditions. The effect of EGR on
durability is still being investigated.
EGR can be achieved by recycling the exhaust gases from the
exhaust to the inlet manifolds. Limited EGR is obtained by changing
the valve overlap. The optimum percentage of EGR required to reduce
NO varies with load. Efforts are being made to optimize the EGR at
different loads to minimize the penalty in fuel economy and the
emissions of HC, CO and smoke.
c. I nj e c_tion timing -- Retarding the injection is an effective
way to reduce the NO emissions because of its effect on maximum
temperature and residence time. Retarding the timing also affects
the HC and CO emissions. Results reported by Opel on the Opel Rekord
diesel car, using the 1975 FTP are shown in Figure 11.4. By retarding
the static injection from 6 BTDC (before top dead center) to 1.5
BTDC, NO emissions dropped by 30% (from 2.47 g/mi to 1.73 g/mi),
A
while the HC and CO emissions increased by 44% and 337=., respectively.
Results obtained from Perkins, given in Table 11.2, show
the effect of retarding the injection timing by 4 with respect to
the standard timing of 21 before top dead center.
-------
143
1.9
o
X
u
Q
o
o
36
28
34 32 30
OVERALL AIR/FUEL RATIO
FIGURE 11.3 Effect of EGR on Opel Rekord Diesel Car (1975 FTP).
26
0,3
Source: Reference 99
-------
144
0.6
1.7
FIGURE 11.4
12345
STATIC INJECTION TIMING C'BTC)
Source: Reference 99
-------
145
TABLE 11.2
Effect of Injection Timing on Emissions from Perkins 154 Engine
in Ford Zephyr Car (CVS Cycle)
Standing Timing Retarded Timing % Change
21° BTCD 17° BTDC
g/rni g/mi
HC 0.46 0.66 + 43%
CO 2,79 3.78 + 35%
NQx 2.33 1,73 - 267,
REF. 100
Perkins reports that the change in fuel economy caused by
this injection retard is within +670 (which is their production
tolerance), and that there has been no problem in meeting the smoke
levels regulated by the European governments.
Retarding the injection is effective in reducing NO , but
,A
causes an increase in HC and CO. The 1978 emissions standards cannot
be achieved by diesel-powered cars by using either injection retard
or a combination of injection retard and EGR.
d. Other controls -- Other techniques used to reduce the NO
emissions are control of the air/fuel ratio at light loads, use of
97
water injection, use of fuel additives (Ref. 98 p. 749), use of
low compression ratios together with supercharging, and modifications
in the fuel-injection system and combustion-chamber design.
e- Summary — In summary, the automotive diesel engine
manufacturers are uncertain that they can meet the 0,40 g/mi standard
for NO in the future, even in an experimental engine. They feel
x
that the diesel engine can meet a level of NO = l.i>-2.0 g/ni with
JV
little changes in the design of current production engines, without
any penalty in fuel economy. Ricardo and Co. Engineers, in a recent
-------
146
102
report to EPA, indicated that a conventional, naturally aspirated
swirl-chamber diesel engine, in a 3,500 Ib vehicle, should be able to
achieve HC = 0,41 g/mi, CO = 3.4 g/ml and NO =1,5 g/mi. Some EGR
may be necessary to ensure a sufficient margin for production tolerances,
It is anticipated that levels of NO equal to 1.0 g/mi, or
even as low as 0.6 g/mi, might be reached in the future if sufficient
research is made to optimize all the NO control techniques,
.X
11.3 Monr egu.1 a ted_Emi s_s ions
The nonregulated emissions studies in this Section are:
particulates, benzo (a) pyrine, sulfur dioxide, sulfuric acid,
aldehydes and ammonia. Many of these nonregulated pollutants are
as harmful or even more harmful than the three regulated species. It
is expected that some of these undesirable species will be regulated
in the future,
a» Farticulates -- Particulates from diesel engines appear as
blue and white smoke under cold-running conditions and low loads, and
as black smoke near full-load operation. The blue and white smoke
contains unburned and partially oxidized fuel, and the black smoke
is mainly carbon.
93
Figure 11.5 shows the airborne particulate emissions in
grams per mile on the 1975 FTP from three diesel powered cars, two
American 1975 gasoline-powered cars, and a PROCO-Capri car. The two
gasoline cars are equipped with catalytic converters. In one of the
gasoline cars, the aged catalyst increased the particulate emissions
by 267%. The PROCO-Capri car produced more particulates than the
gasoline cars. The diesels produced the highest concentration of
particulate emissions.
The proposed level of 0.1 g/mi over the constant-volume-
sampling cycle during the federal testing procedure is difficult to
achieve by the diesel engine, A proposed method to reduce particulate
-------
L47
0.6
0.4
0.2
1
o
Q.
(-
LL
UT5
r-
UJ
1 — n in
< o.io
_l
U
p 0.08
EC
w
?3
O
•*•
u
CD
•C
O
a_
<
4.
>
m
ra
U
JT
•a>
LL
+
"O
O
u_
'<
+
>
•Si
+*:
m
Q
"O
lu
w
<
+
"D
a
u.
FIGURE LI,5 Airborne Particulates Emitted from Diesel and Gasoline
Powered Cars,
Source: Reference 93
-------
148
102
emissions is a soot filter (non-catalytic) which would hold soot
particles emitted at part loads and burn them at high loads when the
exhaust temperatures are high enough to cause their oxidation.
b, Benzo(a)pyrine -- Benzo(a)pyrine (BAP) is an undesirable
carcinogenic species emitted from combustion engines. Among the
factors which affect its concentration in the engine exhaust is the
concentration of aromatics in the fuel. Without adding tetraethyllead
to the gasoline, the concentration of the aromatic compounds in the
fuel has to be increased to arrive at a fuel with a reasonable octane
number and combustion characteristics. This might result in an
increase in BAP emissions in the gasoline engine exhaust in the future.
A comparison between the BAP emissions in three diesel-cars
and for gasoline cars is shown in Figure 11.6 for 1975 FTP cold start,
103
and in Figure 11.7 for 60-tnph, steady-state conditions,
BAP emissions in the diesel exhaust are fairly low under
C'-irtibined cold starting and SO-mph, steady running if compared with
the gasoline engine. The diesel-engine BAP emissions are of the same
order of magnitude as the stratified-charge engines.
The above observations are for a limited number of vehicles;
additional data covering a larger number of vehicles are needed to
i-tudy the BAP emissions from different types of automotive engines,
c. Sulfur compounds — The concentration of the sulfur compounds
in Che exhaust is directly related to the sulfur content of the fuel,
iHffi Federal Register specifies the sulfur content to be 0.05%-Q.2Q%
for type 1-D and 0.2%-0.5% for type 2-D diesel fuel and less than 0.1%
£or gasoline. Figure 11.8 shows the sulfur dioxide and sulfuric acid
n?ss emissions in grams per mile for two gasoline-and one diesel-
93
powered car, and the percent of sulfur converted to H SO,, The
2 4
: :i;s are at 60 mph, steady-state running conditions. The H.SQ, mass
•missions are almost the same for the diesel and gasoline engines, in
-------
149
360 r-
320-
280 —
Diesel:
Gasoline:
1. Mercedes
2. Opel
3. Peugeot
1. 72 Pontiac
+• Catalyst + Air
2- Ford
(.41.3.4,3.1)
3. 11 Ford
•*• Fresh Catalyst + Air
1. 72 Ford
-t- Aged Catalyst + Air
E 240
Q.
Q.
ST
S 200
LU
z
LU
-------
150
360
320
280
"§
- 240
CD
LU
111
£E
200
5 160
N
120
80
40
Diesel:
Gasoline;
Stratified
Charge:
£L
Mercedes
Opel
3. Peugeot
1. 72 Pontiac
+ Catalyst -t- Air
2. Ford
1.41,3.4,3,1}
3. 72 Ford
+• Fresh Catslyst +• Air
4. 72 Ford
+ Aged Catalyst +• Air
1. Cricket TCCS
2. 74 Ford Capri Proco
T3
OJ
| |
in O
FIGURE 11.7 Benzo(a)Pyrene ImiaBlons from Different
Automotive Engines at 60 mph Steady Running Conditions.
Source: Reference 103
-------
151
_ .008,- p-, PI F
JE
c?
X™ .007
.25
.20
4 '15
CM
0 .10
.05
0
Q
£ 50
cc
LU
> 40
I 30
Z 20
LU
£ 10
LU
°- o
-
-
-
-
1—1
j— 1
n
—
—
r — i
n n
"ai +~* *— •*-
S £ < "
Qeo ~*~ "w" ?
*^ o w> •*-
* 0 .2-2- S
^ .1 ? S u c
° i ^ | s -" =
•| < » g o ~
FIGURE 11,8 Sulfur Compounds Emissions from
Different Cars.
Source: Reference 93
-------
152
spite of the fact that the sulfur content of the diesel fuel used in
these tests was 10 times that of gasoline. The SO emissions in
diesel exhaust are about three or four times that of the gasoline
exhaust.
The control of SO and H SO, emissions in the diesel exhaust
can be achieved in the refinery by reducing the sulfur content of the
fuel. This may cause an increase in the fuel cost,
d. Aldehydes -- The aldehydes are partially oxidized hydrocarbons
and are mainly formaldehyde. Other aldehydes emitted from combustion
systems are higher aliphatic aldehydes, aromatic aldehydes, and
aliphatic ketones.
All of the results in this Section are reported as formalde-
104
hyde HCHO, The aldehyde emissions are given in Table 11.3 for
tvo cars equipped with diesel engines, two with models of Wankel
engines, four vith gasoline engines, two with stratified-charge
103
engines, and one with a gas turbine. The results are for the
emissions during 43 minutes of the Modified Federal Cycle Cold Start
(MFCCS) and one-hour, steady-state, 60-mph hot start. The results
for the Honda and Opel Diesel (reports 1 and 2 in Table 11.3) are for
the original Federal Cycle Cold Start. The MFCCS aldehydes are
plotted for the Peugeot and other cars in Figure 11.9. It is noticed
that the cars powered with engines using a heterogeneous mixture
(except for Ford PROCO) produce higher aldehyde emissions. The Ford
PROCO car is equipped with a catalytic converter.
The aldehyde emissions under the steady-state, 60-mph test,
are shown in Figure 11.10.
The contribution of the aldehydes to air pollution should
not be overlooked since their specific reactivity is higher than many
unburned hydrocarbons in photochemical smog formation. Also, their
effect on health and plant damage is worse than many unburned
, , , 106
hydrocarbons,
-------
153
TABLE 11.3
Aldehydes and Ammonia Emissions from Different Types of Cars
HCHO
PPM
Report
No.
1*
2*
3
4
5
6
7
8
9
10
11
12
13
14
15
16
L7
Vehicle
Honda Prototype
Civic CVCC engine
1973 Opel Diesel
Peugeot, 4 Sp. trans.,
Diesel Fuel #2
RX2 Mazda D1527
(Thermal Reactor and
a reactor by-pass) air
pump and EGR
EPA Williams Gas Turbine
Yellow Mazda RX3
(Equipped as in Rep. #4)
72 EPA Ford, durability
Catalyst, Veh. 24A51
72 EPA Ford, SLAVE
Catalyst, Veh. 24A51
Mazda D1527 RX2 Silver
(Equipped as in Rep. #4)
Pontiac 1972 GM 2477
with 1975 hardware with
30,768 miles
Yellow Mazda RX3
(Equipped as in Rep. #4)
EPA Ford, 1973, A 342-25
(designed for HC = 0.41,
CO = 3.4 and NO =3.1)
X
Mazda RX3
(Equipped as in Rep. #4)
1974 Ford Capri EPA 019L
(PROCO)
EPA CRICKET TCCS #8
(with catalytic converter)
EPA CRICKET TCCS #8
(with catalytic converter)
Mazda RX3 7,226.0 miles
MFCCS
1.7
17.5
602.5
924.6
349.1
381.6
14.67
74.04
862.9
21.41
345.56
71.67
592.9
38.86
524.6
805.2
665.7
60 mph
S.S.
64.5
18.5
253.9
2,341.6
80.53
(50 mph)
1,541.3
3.1
26.29
1,385.1
23.3
1,479.8
149.83
1,564.1
31.46
181.9
204.1
NH3
PPM
MFCCS
3.5
19.4
11.1
8.8
15.14
9.32
3.37
2.52
5.81
20.7
10.9
25.31
14.03
6.53
1.72
1.32
5.74
60 mph
S.S.
9
38.9
7.28
32.9
28.20
89.37
0.88
0.75
32.5
17.35
36
7.28
36.5
13.67
1.29
.57
'^Reports 1 and 2 were on the original federal cycle cold start.
REF 103
-------
154
Q.
Q.
u
X
1,000
800
600
400
200
TOO
80
60
40
20
10
8
6
1
o
u
I-
8 n
A -
<
4-
O
•a
O
LL
O
8
CL
D.
-------
155
1,000
800
600
400
CO
o
o
200
100
80
- 60
^ 40
0
X
0
X
20
10
8
6
4
2
1
—
_
—
—
"
—
—
—
—
—
—
o
•i-
15
O
-i-
re
C
o
o_
•1
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O
-C
u_
-i-
o
U-
CM
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15
O
c&
+
6
u.
(M
U
O
—
FIGURE 11.10
Conditions.
HCHO for 60 mph Steady Running
Source: Reference 103
-------
156
e. Ammonia emissions — The NH emissions from the dieseL and
L03
other engines are shown in Table 11,3. It is noticed that NH
is emitted from all the combustion engines, A conclusion for the NH
characteristics of each engine is difficult to make at this stage,
because of the limited amount of experimental data,
11.4 Fuel Economy
The better fuel economy of the diesel engine over the gasoline
engine is the result of its higher compression ratios, higher air/fuel
ratios, and the absence of the throttle valve for load control in the
diesel. Accordingly, the superior fuel economy of the diesel is at
part loads.
The following figures show comparative economy results for diesel-
and gasoline-powered cars, in many application. Figure 11.11 shows
the results submitted by Daimler-Benz (Ref.98 p. 769) for the miles
per gallon of the MB220D diesel and the 1975 MB230 gasoline engine
under steady-state conditions and at speeds up to 75 mph. Both cars
have an I.W. = 3,500 Ibs, The savings in fuel consumption in the
diesel car varies from 53% at 30 mph to 32% at 70 mph. Under the CVS
test, the MB220 diesel averages 23.6 mpg as compared to 13.9-17.2 mpg
for the 1975 gasoline engine; i.e., an average saving of 27% to 4-1%
in fuel consumption. Recent results obtained from EPA Ann Arbor
show that the 1975 MB240D diesel car averages 23 mpg, which makes it
as economical as the MB220D.
It should be noted that part of the fuel saving in the above
comparison is caused by the lower horsepower of the diesel engine as
99
compared to the gasoline engine. A comparison by Opel, based on
engines of equal power output fitted in the same car, is given in
Table 11.4.
-------
60
50
CL 40
o
u
30
LU
.? 20
10
157
Model: MB 220D Diesel
Model: MB 220
Gasoline, Europe
Model: MS 220 Gasoline
Model Year 1972
Model: MB 230 Gasoline
Model Year 1975
_L
J_
10 20 30 40 50
SPEED (mph)
60
70
80 90
FIGURE 11.11 Comparison of Fuel Economy at Road Load for Mercedes Diesel
and Gasoline Cars,
Source: Reference 98
-------
158
TABLE 11.4
Comparison Between Opel DieseJ^and Gasoline Cars
Diesel Car Gasoline Car
Car Weight, Its 3,070 2,750
Engine Displacement, CC 2^10
Miles Per Gallon
(mixed-duty cycle) 34 27
Saving 21% R£F>
A similar comparison based on equal power is reported by Peugeot
on their 504 diesel and 404 gasoline engines. Here the average
saving in fuel consumption is 26%.
109
A comparison between two foreign diesel cars and an American
car, all having the same weight (3,000 Ib), is shown in Figure 11,12
for steady-state operation and in Figure 11,13 for city, suburban, and
average-driving conditions. Here the average saving in fuel consumption
is 367, for the two diesel-powered cars. It should be noted that a part
of this saving is caused by the use of manual transmissions in the
diesel cars as compared to an automatic transmission in the gasoline
car.
The saving in fuel consumption in taxi application in two
110
European cities is shown in Table 11.5.
-------
159
S
o
z
o
o
HI
50
45
40
35
30
25
20
15
20
73 Peugeot
4 Speed,M/T
73 Opel Rekocd
4 Speed. M/T
74 Mustang
3 Speed, A/T
30
40 50
SPEED (mph)
60
70
FIGURE 11,12 Comparison of mpg for Different Cars Under Steady State
Conditions.
Source; Reference 109
-------
160
City
30
20
10
n
en
a
,§ 30
8 20
in
10
Suburban
30
20
10
Average
so
Q.
W
53.
T3
O
-^
ED
<- o
O O
HI o
CD *
3 O
Q)
a)
a»
Q.
W
CO
Cf) o
£• o
5 o
FIGURE 11.13 Comparison of mpg for Different Cars
Under City, Suburban and Average Driving Conditions,
Source: Reference 109
-------
161
TABLE 11.5
Fuel Economy in Taxi Application
Miles per gallon
London Taxi
Paris Taxi
Diesel
30.6
31.4
Gasoline
15.9
21.7
Saving
48%
317, _ „
REF. 110
Similar savings in fuel consumption have been reported by replacing
the gasoline engine with a diesel engine in U.S. Post Office one-half,
one-and five-ton vehicles and in vans equipped with Perkins
A- • 10°
diesel engines.
Part of the higher miles per gallon for the diesel-powered
car is caused by the higher energy content of one gallon of diesel
fuel as compared to the same volume of gasoline, as shown in Table 11.6
(Ref.98 , p. 850).
TABLE 11.6
Comparison Between Diesel and Gasoline Fuels
Average mass Average BTU
Fuel j>er gallon per gallon
Diesel 7.1 137,750
Gasoline 6.0 123,500
REF. 98
The increase in the energy content of one gallon of diesel fuel is
127, above that of gasoline.
-------
162
From a total energy point of view, the energy expenditure in
producing the fuel at the refinery should be taken into consideration,
Diesel engines can use a wide range of distillates which are produced
at a lower cost than gasoline.
In summary, the average saving in fuel consumption by using the
diesel engine instead of the gasoline engine in passenger cars varies
between 257= to 50%.
11.5 Initial and Maintenance Costs
Diesel engines initially cost about 50% more than gasoline
engines. Half of this difference is attributed to the high cost of
102
the fuel-injection system, and is partially caused by its limited
112
mass production. For a diesel engine to have the same power as a
gasoline engine, it should have a larger displacement volume, since
the air utilization is less. Also, it should have heavier parts to
stand the much higher gas pressures produced in the cylinder as a
result of the higher compression ratio used. These, too, increase
production costs of the engine. The heavier starting motors and
batteries required to overcome the high compression, pressures and to
the production cost of the diesel-powered cars.
However, the maintenance cost for the diesel engine is lower
than that for the gasoline engine. The injection system does not
require the frequent maintenance and replacement of parts experienced
with the ignition system and carburetor of the gasoline engine,
although there is a slightly higher cost for each service. On the
other hand, routine maintenance (oil and filter change) is more
frequent for the diesel engine,
Daimler-Benz reported the initial and maintenance costs for
113
their MB 1975 gasoline and diesel cars. These costs are given in
Table 11.7. The maintenance cost includes general maintenance (spark
-------
163
TABLE 11.7
Initial and Maintenance Costs and Performance
of Mercedes 1975 Cars *
Diesel Gasoline
240D 2.3L
Vehicle Weight, Ib
Horsepower
California
Model
3,500 3,200
65 95
Federal
Model
3,200
95
Weight-Power Ratio
Ib/HP
Fuel Economy
mpg
Acceleration time, sec
60 mpg
Initial Cost
Maintenance Cost for
100,000 miles
Initial Price
(1974 Model)
Total Cost for
100,000 miles
(assuming 1974
Model Prices)
6,8
21-22
24.6
$1,153
$8,715
$9,868
2.6
16.2
13.7
$2,590
$8 420
$11,010
2.6
15.5
13.7
$2,590
$8,420
$11,010
-'The initial cost for the Mercedes 1975 cars had not been
announced by the company at the time of writing this report.
The initial prices for the 1974 models are used for comparison.
REF 113
-------
164
plugs, tuning, oil changes, etc,) and two catalyst changes for the
gasoline car. The larger cost differential between the two cars in
1975 is the high cost for the catalyst change which was quoted at $600
for this six-cylinder and $800 for the eight-cylinder gasoline engine.
The 1974 maintenance costs are $1,132 for the diesel and $1,062 for
the gasoline engine,
At 23 mpg for the 1975 diesel car and 16 mpg for the 1975
gasoline car, and at 45c/gal for the diesel fuel and 55c/gal for
gasoline, the fuel cost for 100,000 miles would be $1,957 and $3,438
for the diesel and gasoline cars, respectively. For the sake of
comparison, considering 1974 model prices, Che estimated total initial
maintenance and fuel costs are $11,825 for the diesel and $14,448 for
the gasoline car. This means a saving of 18% to the owner of the
diesel-powered car.
The superior economy of the diesel-powered car over the gasoline-
powered car is manifested in applications involving part-load operations
For example, taxicab fleet owners in London and other cities in Europe
had to shift from the gasoline to the diesel engines to make a profit
while keeping the fares within the limits imposed by the local
authorities,
Diesel engines proved to be economical in taxicab fleet
operations even in countries x^here the price of the diesel fuel is
equal to or slightly higher than gasoline fuel, such as in Great
Britain, In other countries where diesel fuel is less expensive than
gasoline, the savings increase proportionally.
The present higher initial cost of the diesel-powered car over
the gasoline car is expected to diminish in the 1975 model cars and
those that follow. For 1975 California cars and 1977 nationwide cars,
the gasoline-powered cars should be equipped with catalytic converters
and feedback systems. Some of the gasoline engines will be equipped
with fuel-injection equipment. All these add-on devices will increase
-------
165
the initial and maintenance costs of the gasoline-powered cars and make
the diesel-powered car more economical.
11.6 Driveability -- The driveability of two Mercedes diesel
automatic transmission (A/T) vehicles (1969 and 1974 models), a 1973
manual transmission (M/T) Opel Rekord and a 1973 M/T Peugeot were
compared to the driveability of a 1973 Pinto and a Honda A/T CVCC
109
vehicle. The results are shown in Figure 11.14, The A/T diesels
were better than the one A/1 gasoline engine in the following three
types of evaluation: minimum driving ratings, drive ratings average,
and the idel quality rating. The M/T diesels were better than the
Honda CVCC M/T in two categories. However, the Honda CVCG M/T was
better in idle quality. Daimler-Benz reported that the driveability
of their diesel-powered vehicle is the same as their gasoline-powered
vehicle,
11.7 Intrinsic Problem_Areas
a- S^art^ing -- Automotive diesel engines which can meet the
emissions standards have a prechamber (Mercedes) or swirl-type
(Peugeot and Opel) combustion chamber. These types of combustion
chambers need a starting aid in the form of a glow plug. Because
the glow plug should reach a high temperature before cranking the
engine, some delay in starting is experienced. At present, research
is being done on a high-intensity glow plug to reduce starting delay,,
b. Noise -- The diesel engine is inherently noisier than the
gasoline engine, particularly after cold start and during idling. This
will be discussed under the noise emission classifications of exterior
and interior noise.
Figure 11.15 shows a comparison made by the Ford Motor
Company between the exterior noise levels of three diesel-powered cars
-------
166
o
7 [-
>w
cc o
°? 6h-
N
z
5 5 h
(3 I-
fy rr
LU
< 5
D
O
LU
n
Q
O
111
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e
m
Q
S
in
a;
EC
"S
CL
cn
en
IN
O
^J
C
b.
O
o
o
10
•
FIGURE 11.14 Comparative Drivability of Diesel Powered
and Other Cars.
Source: Reference 109
-------
w
o
pa
fD
l-l
(D
3
O
(D
O
VD
EXTERIOR NOISE LEVEL, dB{A)
to
H
H'
O
H
O
H-
n>
i->
03
IT)
O
g
a
H-
Hn
Hi
(D
ft
h
in
CO
o
00
en
6B Mercedes 220 D
A/T
& 73 Opel Rekord 2700 D
M/T
73 Peugeot 504 D
M/T
74 Maverick, 260 CIO
M/T
74 Pinto, 2.3L
w/Sport Accent, M/T
74 Torino 351-2V-W
A/T High Series
I I
1 1
3 O
• 13
-* O
-------
168
109
and three American gasoline-powered cars. This comparison is
according to the SAE Standard J 986a test procedures.- This test
calls for a wide-open throttle acceleration from 30 mph to maximum
engine revolutions-per-minute over a distance of 100 ft, with a
microphone stationed 40-50 ft away. The results show that the three
diesel engines have lower sound levels than the 1974 Torino and have
the same sound level as the 1974 Pinto. Also, these engines meet
the present California standards, and those proposed for 1975. The
1973 Peugeot meets the proposed 1978 California standards. The 1969
Mercedes and the 1973 Opel are 0.5 dB above the proposed 1978 California
standards,
Recent comparative noise results reported by Southwest
94
Research Institute are shown in Figure 11.16 and Table 11,8 for
cars of different makes. Figure 11,16 indicates that some diesel-
powered cars produced less exterior noise than the gasoline-powered
car and others produced more noise. Also, the diesel-powered cars,
except the Mercedes, meet the proposed 1978 California noise standards
of 75 dbA. The Mercedes car exceeds the proposed 1978 California
standards by 2 dbA, and the Capri PROCO exceeds these standards by
dbA.
A comparison between diesel-and gasoline-powered cars of
the same make are shown in Figure 11,17. The noise levels of the
Mercedes 220D diesel and 220 gasoline cars are shown in Figure 11.17
for different driving modes (Ref, 98, p. 773). The diesel produces
noise levels of 1 dbA to 5 dbA higher than the gasoline engines. The
diesel car is particularly noisy during engine start up and idling.
The noise levels of the Peugeot 504 diesel car are higher than the
*SAE -- Society of Automotive Engineers
-------
169
80
03
-a
75
—
O
z
ct
70
65
T>
O
3)
CC.
Q.
O
O
O
in
o
4>
o
(N
0)
T3
V
z
c
(
o
FIGURE 11.16 Exterior Noise Levels from Different Cars,
Source: Reference 94
-------
// Diesel Engine
I j Gasoiing Engine
m
T3
LLJ
LLJ
CO
CC
O
X
LLJ
80
70
60
50
30
2
Engine !d!e Vehicle Start St V20 31 mph 62 mph 44 mph
Start normal quick § 49 3rd G. 4th G. 4th G.
FIGURE 11.17 Comparison of Exterior Noise Levels for 2.2 Liter
Mercedes Gasoline and Diesel Cars.
Source: Reference 98
-------
11. 8
Comparison. Between. Exterior and Interior Noise Levels o£
Diesel-and-Gasoline-Powered Cars
Date Tested
SAI J986a
Accel Driveby
Exterior
Interior ,-, ,
1 1 )
Blower On v '
Off
48,3 km/hr Driveby
Exterior
Interior ,, .
f i \
Blower On v '
Off
Engine Idle/,,,
Exterior
Interior . -.
Blower On ' ^
Off
Datsim
Nissan
3-6-74
74.8
84
83.3
63.3
71.3
69.5
79
67
66.8
Mercedes
220D
3-5-74
77
78,8
74,3
62
73.5
63.5
66
71.5
51.5
Capri
Std
3-6-74
73
82.3
81.5
o\
58. 1W
70.5
65.8
63
70
54
Peugeot
504D
3-26-74
70.8
80
78.5
61.3
72.3
66.5
68
70
52.3
Opel
Rekord
3-26-74
67.5
73.8
73.5
62.5
70
69
72
70
53.3
Capri
PROCO
3-26-74
76
83
83
58.5
72.3
70.5
63.5
71
66
Capri
Std
3-26-74
73.3
83
82.5
58
71.8
66.5
57.5
70.5
53
(1) Windows Up, Fresh Air Blower on High
(2) at 7.62 m
(3) at 2.54 m
REF 94
-------
172
PeugeoL 504 gasoline car by 4 dbA during idling and 2 dbA at 31 mph.
The two cars have equal noise levels at 50 mph and 62 raph. At 74 mph,
the diesel car is noisier by 2 dbA, (Ref. 98, p. 839).
Table 11.8 also shows the results of many tests conducted
by Southwest Research Institute according to the Federal Clean Car
94
Incentive Program. These results also show that the exterior drive
by and idle noise for the diesel cars is higher than the gasoline
powered cars,
109
A comparison between the steady-state interior noise
levels (A-weighted-dbA) of three diesel vehicles and those of a 1974
Torino and a 1974 Pinto 2.3L are shown in Figure 11.18 for speeds
ranging from 20 mph to 60 raph on a smooth asphalt road. The results
show that the Torino is fairly quiet compared to the diesels, but that
the Pinto has nearly the same noise levels.
It should be noted that the interior noise depends to a
great extent on the packaging of the engines, the structure of the
car, interior design and blower noise.
Table 11.8 shows that some diesel cars have lower interior
noise levels than gasoline cars and that this noise level depends on
whether the blower is on or off.
The noise level of diesel engines may be reduced by
modifications to the fuel injection system, changes in injection
timing, use of pilot injection, structural changes, basic changes in
engine design (such as using more cylinder of smaller bore, etc.),
intake and exhaust-manifold modifications, and engine isolation
techniques,
c. Odor -- The odor produced by the diesel engine is caused by
products of the auto-ignition process. Even gasoline engines produce
odor if they run on or "diesel".
Little research work has been done to define which of the
stages of the auto-ignition process produce the characteristic odor.
-------
173
80 r-
co
TJ
0
LLJ
01
_l
LU
>
LLJ
LLJ
01
CC
O
-------
174
One research program, using n-heptane-air mixtures, in a motored CFR
engine, indicated that odor is the result of quenching the second stage
97 94
(cool flame) in the auto-ignition process. Table 11.9 shows
the results of a comparison of the exhaust odor from four diesel -
powered cars, two gasoline cars and a PROCO Capri car. These exhaust-
odor results are for 10 driving modes covering the whole range of
loads and speeds. The averages of all 10 modes show that the odor
from the diesel cars is, in general, higher than that from the gasoline
or PROCO cars,
The use of exhaust-catalytic converters to reduce odor,
114
and other incomplete combustion products in the diesel exhaust, is
still in the research stage. It is not expected that it will be
applied to the actual engine in the near future.
Further basic research is needed to study odor control,
d. Low _power-weight ratio — The diesel engine produces less
power than the gasoline engine of equal displacement, for two reasons.
First, the overall fuel/air ratio in the diesel is always leaner
than the stoichiometric ratio. The limit to the increase in fuel/air
ratio is smoke production. Second, the maximum rated speeds in
diesel engines are less than in gasoline engines. The limit here is
the short time allowed for fuel injection, evaporation, mixing and
combustion for proper engine operation. Mechanical-stress considerations
also limit the speed of the diesel engine.
The low power/weight ratio causes the diesel-powered car to
take a longer time for acceleration. Table 11,7 shows that time for
acceleration from 0 to 60 mph is 13.7 seconds for the Mercedes 2.3L
gasoline engine, and 24,6 seconds for the 240D diesel car. For the
Peugeot 504 diesel this time is 23,6 seconds, and it is 16.2 seconds
for the 504 Peugeot gasoline engine.
-------
175
TABLE 11.9
Comparison of Odor from
Type
Fuel
Diesel
Gasoline
Car
Datsun-Nissan W
S
Mercedes 220D
Peugeot 504D
Opel Rekord
Ford LTD
Standard Capri
PROCO Capri
Diesel -and Gasoline -Powered Cars
Six Steady
States
3.4
3.2
3.0
5.2
3.9
1.5
3.0
1.0
Idle
2.9
2.7
3.1
4.8
3.3
1.2
3.3
0.7
Three
Trans ,
4.7
4.6
3,7
5.7
4.1
1.5
2.9
1.6
All Ten
Conditions
3.8
3.6
3.2
5.3
3.9
0.6
3.0
1.1
REF 94
-------
176
Turbocharging is an effective tool for improving the power/
weight ratio of the diesel engine, Turbocharging increases the
maximum power, torque and rated speed of the engine. This improves
the acceleration characteristics of the vehicle. The effect of
turhocbarging on fuel economy and emissions from the diesel-powered
car is presently being studied by many manufacturers. The present
attempts are being made by adding a turbocharger to existing diesel
engines without lowering their compression ratio or optimizing the
injection and combustion processes. The results of these attempts
are not conclusive. The penalty in fuel economy at idling and low
loads as a result of turbocharging depends on the design of the intake
and exhaust systems and the degree of matching the turbocharger to the
engine. The effect of turbocharging on the emissions during a FTP
cycle has not been assessed,
11,8 Conclusions
a. Technological feasibility of meeting the different emission
standards:
(1) Diesel engines, currently mass-produced to power
passenger cars of 3,000 Ib to 3,500 Ib3 can meet the
1977 standards without EGR, add-on exhaust treatment
or feedback systems.
(2) There is no penalty in the initial cost, maintenance
cost, or fuel economy of these engines in meeting
these standards,
(3) These diesel engines proved to be the most economical
power plants as far as fuel consumption is concerned
and are as reliable and durable in the field as the
non-controlled gasoline engine.
-------
177
(4) The total cost to the owner for one of these mass-
produced 1975 cars, including initial, maintenance and
fuel cost for 100,000 miles, will be less than that for
the equivalent gasoline-engine car.
(5) No extraordinary maintenance is required in the field
during the useful life of the vehicle due to the absence
of catalytic converters and feedback systems and the
high durability of the diesel engine,
1978^ Nationwide standards
(1) Based on the presently known technology, it is not
feasible for the diesel-powered car to meet the 1978
NO standards of 0.4 g/mi,
Jv
(2) If the NO standard is relaxed to 1.5-2 g/mi, many
Jt
currently mass-produced, diesel-powered cars would be
able to meet the standard without any penalty in initial,
maintenance or fuel cost. Thus, the diesel-powered
car would be superior to the gasoline version in total
cost to the customer, and in reliability and durability,
(3) With the application of EGR, injection-system modification
and injection retard, it may be possible for currently
produced diesel-povered cars to meet NO levels of
1.0 g/mi,, but this may result in a penalty of 5% to
15% in fuel economy and power. The effect on
durability of the engine has not been assessed.
(4) Levels of NO , slightly less than 1.0 g/mi (but not less
it
than 0.6 g/mi) might be reached by diesel-powered cars
if sufficient research is conducted to optimize all the
NO -control techniques.
-------
178
Problem areas
(1) Intrinsic problem areas in the diesel powered cars
which deserve further research are; participates,
odor, noise, and lov power/weight ratio.
(2) The future standards for the nonregulated emissions
should of course, take into consideration the harmful
effect of the pollutants rather than the total mass
of the emissions. For example, one gram of aldehydes
may be more harmful to the health and environment
than one gram of paraffinic hydrocarbons. Also, the
total mass of the particulate emissions may be high
in the exhaust of one type of engine, but the mass of
harmful species (such as BAP) may be low,
(3) The relaxation of 1978 NO emissions should be decided
•x.
on as soon as possible. The lead time needed for
manufacturing is on the order of five years.
-------
12, ALTERNATIVE POWER PLANTS FOR AUTOMOBILES
12,1 introduction
Activities in alternative power-plant development for automobiles
have continued in the two years since Reference 116 was written. Many
of the problem areas have been more firmly stated and some of the less
applicable power plants have been weeded out. The engine characteristics
and development times have become more firm. It is clear that there are
no high-performance alternative power plants that can go into mass pro-
duction before the 1980's.
Alternative heat engines in their major forms are gas turbines,
Stirling engines, and Rankine engines. These can be categorized as
continuous-combustion engines in which a fire is established and heat
is continuously supplied to the system until power is no longer needed.
There are a number of other engines that fit into the spectrum repre-
sented by these three major types, such as several forms of reciprocating
Brayton-cycle engines and super-critical-fluid Rankine cycles. In this
Section, concentration will be with the major types. These heat engines
can use energy stored in the form of liquid or gaseous fuel. Also, the
Stirling and Rankine engines can use energy stored in any fuel and in
the form of heat.
Storage batteries have been used extensively for over a century,
and these can be used in modified form for powering automobiles without
the aid of heat engines. Also, flywheels have been used for over a
century, but more recently they have been used to supply power to the
drive wheels of busses. With the use of new materials and recent
technology, high-performance flywheels can now be designed to be used
directly, or as a mechanical energy-storage system for powering an
electrical drive for automobiles.
Hybrid systems are combinations of two or more different kinds
of power plants or of different versions of similar power plants. The
aim of hybrids is to allow the complete system to perform, according
to the best features of each part. Those hybrids that have
179
-------
180
been given the most attention in the last few years are battery-heat
engine combinations. Some consideration has also been given to
combining two different kinds of batteries in an electrical drive
sys tern.
Alternative engines for automobiles are in an embryo state of
development. While gas turbines, Stirling engines, steam engines,
advanced lead-acid battery power plants, and electric-heat engine
hybrids have been running in automobiles, there are none that can be
considered as suitable prototypes for manufacture. That is, the
developers themselves have indicated that at least another generation
of development is required before they will be satisfied that their
particular power plant has demonstrated its full technical, economic
and customer-satisfaction potential. There are no flywheel or
flywheel-hybrid power plants presently operating in automobiles;
and there are no high-performance, battery-powered systems running
in automobiles,
A few examples of experimental continuous-combustion engines
have progressed beyond the dynomometer testing stage and are presently
mounted in automobiles that are either available, or very nearly
will be available, for test driving. These include two Stirling
engines (United Stirling and Philips), three gas turbines (Williams
Research and Volkswagenj Chrysler, and General Motors), and eight
Rankine engines (Carter, Scientific Energy Systems, Steam Power Systems,
Pritchard, Thermo-Electron, Aerojet, Kinetics Corp., and Williams
Brothers). Other cars, such as GM's steam cars and Rover's gas-
turbine car, have operated in the past but their development is now
dormant. Others, such as the Paxve Rankine engine car, are in a
temporary state of dormancy. All of the active engine programs
winose goal is mass application to automobiles are aimed at
•..onionstration and upgrading. Measured performance and engine
actcristics that are considered as the final state of
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181
development do not exist. Therefore, while some data and
quantitative characteristics are reported herein, they are not to be
considered as representative of fully developed engines. Most of
the information is, per force, tempered by judgment of the source
and of the panel of consultants; the conclusions stated throughout
this Section are judgments of the latter.
Similar judgment has been rendered in some cases concerning
batteries and electric drives. This is particularly true for the
high-performance batteries still under development. Also, the
electric drive situation is in a state of flux with final choice of
system not made in most cases.
12.2 Gas Turbine
In comparison -with aircraft and industrial gas turbines, the
automotive gas turbine has a much more difficult job and has
necessitated considerable development effort. Efficiency, low
idle fuel consumption, good off-design performance,, and fast response
requirements have forced the developers to turn their attention to
higher turbine inlet temperatures, simple yet efficient rotating
components and highly effective regenerators. Thrust is not needed
as in jet engines. Steady load as in industrial gas turbines is the
antithesis of automotive gas turbine use. These aspects make the
automotive gas turbine unique.
General Motors demonstrated attainment of 1978 emissions
122
standards in 1974. It used an existing engine (GT 225) in an
automobile weighing 5,000 Ib, running through the federal driving
cycle on chassis rolls. A large variable-geometry combustion was
fitted and was manually controlled from an off-vehicle console. All
four tests made were reported as being below the 1977 limits;
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182
HC CO
grams per mile
0.02 2.7 0.32
from cold starts using diesel fuels. Other developments also show
— 1 9 R
low emissions. ~ Above 2.0 g/mi NO a fixed combustion geometry can
j*t
be used. Achievement of NO as low as 0.4 g/mi requires variable geome-
^ -I O C 1 O t
try, although the Zwick combustion * uses only a very simple flow-
splitter concept. This combustion was tested on a small gas turbine and
yielded the following emissions (translated from g/kg) :
HC CO NOx
grams per mile
0.26 2.7 0.12
There was general agreement among all companies visited that
there was no problem in meeting the hydrocarbon and carbon -monoxide
limits with existing gas turbines, and that a level near 2.0 g/mi NO
X
could he reached with fixed -geometry combustors. The use of variable-
geometry combustors to reach the lower NO limits would entail addi-
tional manufacturing costs of at least $40 (Ford projection) because
of the more complex burner and control system required.
Ford, Chrysler, and GM were in. agreement that gas -turbine
engines, which would be available for production in the 1980's, would
have fuel consumptions in. the federal driving cycle lower than the
average of spark-ignition engines controlled to meet 1974 emissions.
129
Ford, in particular, forecast sharply lower consumption. It felt
that the miles per gallon of production vehicles would be 40% higher
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183
than that of 1974 spark-ignition-engine cars in 1985 and 130% higher
in 1990 (3,000°F TIT). Poor idle fuel consumption has been the
chief cause of poor mileage in urban driving, and the higher TIT
levels projected tend to reduce this deficiency. Calculations
verify that with Ford's projected component performance (turbine
efficiency = 91%, regenerator effectiveness = 92%, compressor
efficiency = 85%, leakage = 2%?0, and pressure drop = 10%), and with a
turbine inlet temperature (TIT) of 2,500°F, that the projected fuel
economy is reasonable to obtain. The component efficiencies listed
above are on the optimistic side, which implies that very careful
development will be required to achieve the above-mentioned fuel
economy. Ceramic turbineSj nozzle rings, combustors, and heat
recovery units are required to achieve the full advantage in fuel
economy.
The most significant change in the outlook for the gas turbine
122 129-131
results from the general agreement among U, S, manufacturers *"'
that it can be a technically superior engine to the spark-ignition
engine at least down to 100 hp, and probably to 75 hp. If Ford's
predictions are confirmed, a 75-hp gas-turbine engine would have a
lower fuel consumption than a 40-hp spark-ignition engine, thus
tending to rule out the use of minicars as a necessity to reach high
mileage.
Moreover, gas turbines of any size are intrinsically long-life
engines, as demonstrated in the aviation industry. Their use will
give an incentive to the design of long-life chassis and to the
consequent reduction in materials use. In contrast, spark-ignition,
internal-combustion engines as used in automobiles are comparatively
short-life engines, with life decreasing as size decreases.
The configuration of the gas turbine for automotive use, which
has been regarded as standard, has a centrifugal compressor, one or
two rotary regenerators, a combustor, and an axial turbine as the
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184
so-called 'gasifier' section, and a separate-shaft axial turbine with
130-136 „...,.
variable-angle nozzles forming the power section. This basic
configuration was used by GM in their demonstration of low emissions.
137
In the last two years, there has been increased study of
122 129
and acceptance of the single-shaft gas turbine concept ' which
achieves considerable simplification by dispensing with the power turbine,
However, some form of infinitely variable transmission is required to
take power from the shaft driving the compressor, whose speed must be
maintained at above 50% design speed. Various types of transmission are
being studied, but nonehas yet been demonstrated with a single-shaft gas
turbine.
Present U.S. vehicle turbines use peak-cycle temperatures in
the range of 1,850°-1,925°F.122'129~131 It is generally accepted129'131
that 2,200 F is achievable with existing technology. It is anticipated
that temperatures will be increased over the next six years to
2,500°F, ' and possibly to 3,000°?, " The most likely means for
withstanding these temperatures in the combustor, nozzle and turbine
is the use of silicon carbide or silcon nitride. Ford, with in-house
and ARPA funding, is developing a dual-density turbine wheel with a
hot-pressed hub and molded blades, both of SiN . Indicative of the
increasing effort on ceramics for gas turbines are References 138-1425
showing the high potential of silicon carbide and silicon nitride.
Alternative ways of reaching high temperatures are to use gas or liquid
cooling and to employ coated refractory (molybdenum) alloys.
Design of gas turbine for the high inlet temperatures required
to achieve competitiveness with gasoline engines is a new science
that is some years away from maturity. Casting and firing ceramics,
use of refractory metals, and strong cooling of blades and nozzles
are all expensive at this time. They are all in the early development
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185
stages for automobile engines. There is no established certainty that
any of these methods of utilizing high turbine inlet temperatures can
be developed for a low-cost engine. Also, there is some feeling among
development engineers that the potential performance gains associated
with higher turbine inlet temperatures will be dissipated by increased
143
losses due to the reduced Reynolds number.
The cost of anti-friction bearings can be high, Chrysler uses
130
plain bearings presently. Gas bearings of the foil type seem
129
attractive as a future development.
Present problems with ceramic heat exchangers have been
identified as due principally to sodium substitution from road and
129
sea salt. Hew ceramic materials will be required. Some potential
candidates have been found and are being evaluated.
Studies have been made, and are continuing, on gas-turbine
costs to the consumer. * f Above 150 hp, it is possible that
131
they could be near competitive with spark-ignition engines, but they
143
become much less competitive below 100 hp. The cost structure is
not clear at this time and must be made firm with more experience in
small gas-turbine manufacturing.
The estimates made in the April 1973 report (Reference 116) still
seem valid—that limited production of gas turbines could start in 1982
and mass production in 1984. These estimates assume an incense and
continuing effort.
The costs of changing the automobile industry's 46 engine lines
to gas-turbine production (ceramic components) have been estimated by
1?9
Ford to be $250 million each, or a total of $11.5 billion. This
cost would be additional to the normal costs of production changes.
Ford's estimates show the possibility of the investment being equalled
by the value of the fuel saved (at about 65 cents per gallon) within
five years.
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186
All foreign manufacturers appear to be well behind U.S. companies
In automobile gas-turbine development. Their predictions are also much
more conservative; reflecting U.S. views of five or ten years ago.
12.3 Rankine-Cycle Engines
Rankine engines for automobiles are basically of four types:
steam with positive-displacement prime mover, steam with turbine
prime mover, organic fluid with positive-displacement prime mover,
and organic fluid with turbine prime mover. Another broad category
of Rankine-cycle engines--those using liquid metals--is not being
considered for automobiles.
Steam has been used the longest of any of the available working
fluids, and reciprocating prime movers have been used the longest with
steam. Other fluids were investigated as the need developed for high
power density in the prime mover and for efficient low-temperature
cycles. Rankine cycles are subject to optimization for peak efficiency,
or reduced size, or reduced cost as a function of fluid and design
conditions. Conclusions based on Rankine-cycle optimization and hard-
116,127,145-164 , ,,, , ^
ware investigations are that steam will lead to the
lightest and most efficient simple Rankine engine for automobiles. The
efficiency of simple steam cycles is generally limited to about 257,
at the best operating conditions; organic Rankine cycles are generally
limited to about 20% at the best operating conditions. Thus, organic
fluid power plants have boilers a minimum of one quarter larger than
equivalent steam plants, and the condensers need to be at least one third
bigger. Many organic fluids also have thermodynamic properties that
require recuperators to be built into the power plant.
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187
The last two years have seen significant development strides
in steam automobile engines. Efficiency has been pushed to near
the probable limit for simple steam engines in at least two development
147,148
programs , and in one of these development programs, the weight
and volume have been brought down to be near competitive with the
147
small engine that it replaced.
Also, the latter engine, described in Table 12.1 (Carter) has
demonstrated in. actual tests that the 1978 emissions goals have been
met with competitive mileage in an auto having an overall weight of
2,750 Ibs:
14.9
HC
CO
NO
X
WT
MPG
0.399
1.08
0.33
415
g/mi
g/mi
g/mi
Ibs
This steam engine has been fitted into a small car (a VW station
wagon). Figure 12,1 shows three photographs of the car and
components. The engine filled the compartment of the air-cooled SI
engine it replaced. In addition, a 35" x 16" x 2%" ram air radiator
mounted at the front of the car is satisfactory to 60 mph. A small
additional radiator with a fan is mounted in the engine compartment.
Fixed cutoff is used. A transmission and variable boiler pressure
is used to vary power and torque to the wheels. The boiler
pressure is allowed to change in response to power demands. Boiler
pressure, water rate, steam temperature, and F/A ratio are all
controlled. These innovations lead to simplified controls. The
steam is held closely (+15 P) to design temperature at all times to
allow the efficiency to be as high as practical over the operating
range. The prime mover is a very light piston engine using a unique
-------
TABLE 12.1
Steam Engine Characteristics
HP
HGT
Fuel Consumption
Emissions
Type
SPS
65
940 Ib
incl, trans ,
1.2 Ib/HP hr
BSFC
0,14 HC, 1.2 CO,
0.22 KOx
(Projected)
4 Cylinder
Double Acting
SES
150 (gross)
904 (Projected)
10 MG
0,18 HC, 0.43 CO,
0,18 NOX
(Predicted)
4 Cylinder
Uniflow
Aero let
60
970 Ib
incl, trans.
0,95 BSFC
(best)
0.1 HC, 0.5 CO,
0,17 KOX
(Projected)
Turbine
(single-stage
Carter
90
417,5 (with
front condenser only)
14.9 tnpg FDC*
(0.67 BSFC to
vehicle dynamometer)
0.4 HC, 1.08 CO
0.33 NOX
(Measured at EPA)
4 Cylinder
Uniflow
Thermo -Electron
111.1 (Fluorinol - 85
•working fluid)
1.3 Ib/HP hr
(10.2 mpg-FDC)
0.17 HC, 0.21 CO,
0.275 NOX
(Predicted)
4 Cylinder
Uniflow
impulse)
CO
CO
S team
Condenser
Compound
Hi Pr Bore = 2.125" (2)
Lo Pr Bore = 4,25 (2)
Stroke = 2.125"
RPM - 2,400 (max)
Valve - variable cutoff
- variable timing
Monotube boiler
- 700 pph
1,000 psia
@ 850 F
6ft2
3 1/2" bore
3 1/2" stroke
variable cutoff
variable timing
Monotube boiler
- 1,200 pph
1,000 psia
@ 1,000 °F
6.32 ft2
4.42" bore
3,00" stroke
Monotube boiler
- 660 pph
500 psia
@ 1,000 °F
3.9 ft2
Fixed cutoff
Monotube boiler
2,000 psia
@ 1,000 °F
2
3.5 ft (approx)
for front condenser
6 ft (approx)
-------
L89
FIGURE 12.1
Rear View of VW with Carter Steam Engine Mounted. The Grill
Covers the Boiler Stack and the Rear Condenser.
The Prime Mover Showing the 4 Cylinder.
-------
190
Continuation of FIGURE 12.1
The Boiler-Burner Assembly.
Source: Reference 147
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191
valving system and uniflow design that lead to high prime-mover
efficiency. Extremely good lubrication is achieved which promises
to lead to very long prime-mover life. A centrifuge is used to
separate oil from the feedwater so that oil will not affect the
design or operation of the boiler and condensers. The flow chart
for this engine is indicated on Figure 12.2,
The demonstrated starting time to high-speed idle is less than
15 seconds. Time to reach driving power is 27 seconds. The emissions
of this engine are not the best that could be expected, but it is not
because of the engine design. Rather, the application of principles
1 O£ I o-7
of combustion design developed in other companies * could easily
reduce the emissions further without affecting the engine in any
significant manner.
Good strides were made in the development of another steam
148
engine designed for a larger car* This engine is presently
mounted on a dynamometer being readied for simulated driving.
Steady-state measurements indicate that the mileage will be near
competitive to 1974 vehicles. Very good emission results are also
indicated. Table 12,1 describes the SES engine.
A third steam engine presently starting driving tests in a
small vehicle (2,500 Ib) demonstrates very good emissions in its
146
preliminary tests. Also, mileage appears to be approaching that
for emission-controlled, gasoline-engine-powered automobiles of the
same weight. Table 12.1 describes the SPS engine and the
characteristics of an advanced version as anticipated by SPS,
The Aerojet steam turbine engine built for the "California Clean
Car" is also described on Table 12.1. It is not as far along as the
others. The Thermo-Electron organic fluid engine is also described
on Table 12.1. This engine development was being supported by EPA
and Ford. Ford has declined to fund this program further.
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192
Fuel In —>
Air In
Water into.
Control
Oil Return
to Crankcase
Water
Pump
Fuel into
Atomizer
I—. Steam
_j_ Out Boiler
Pressure Container
Fy«l~Air Container
Temperature
Container
Variable Pressure Boiler
Water into
Boiler
Plus Gas
Exhaust _
Throttle Valve -HX1
(control purposes only)
12.2 Flow Chart.
Source: Reference L47
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193
Cost is the major unknown factor for Rankine engines. With the
continued development of manufacturing techniques for boilers, with
the use of the simple controls already demonstrated on one of the
147
existing engines, with the use of burners having emissions as low
, , ' ^ t , , 126,127,144,148,149 , . , ,
as has been demonstrated already, and with the use of
147
the lightweight, simple, well-lubricated prime mover discussed herein,
the cost of the engine probably can be brought down to within 507. to
100?o of the equivalent pre-control spark-ignition gasoline engine.
The prime movers and the accessory drives could, conceivably, be less
costly than the equivalent SI engine. The control system demonstrated
147
on the small steam engine in the VW station wagon is the simplest
of the Rankine-engine control systems being developed on EPA or State
of California contracts.
12.4 _S_tjirling_ Engines
Basic findings on the Stirling engine as reported in leference 116
are still valid with some minor modifications. Developments in Stirling
engines for automobiles over the last two years have centered
165,166
around installing two experimental versions in marketable auto frames,
A 175 hp engine has been operating on a dynamometer in the Netherlands
and will soon be mounted in a Ford Torino, and a 100 hp engine has
166
powered a Ford Pinto to as high as 65 mph on a flat track. A CVS
test simulation indicates emissions of an intermediate-size auto will be:
HC CO NGx MPG
grams per mile
0.20 1.20 0,14 14,7
These engines are described in Table 12,2,
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193a
TABLE 12.2
HP
Emissions
Type
Mechanism
Fluid
Rod Seal
Control
Peak Temperature
Engine Efficiency (Peak)
(see plot below)
Radiator Area
Market Goal for
cp^cific Engire
S_Eir 1 ing _ Engine Description
Philips
170
0.20 HC, 1.20 CO, 0.14 NO
double acting
swash plate
hydrogen
roll sock
variable mean pressure
1400°F
32%
automobile
Fuel Economy Map - 4-215 Engine
60 r-
United Stirling
100
double acting
V-4, crankshaft
hydrogen
rod clearance control
variable pressure amplitude
1400°F
25%
3 ft2 <3" thick)
replaces small diesel
o
tr
O
10
1000 2000 3000
ENGINE SPEED (rpm)
4000
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194
What is now apparent for Stirling engines is that by tailoring
the efficiency slightly, an engine of appropriate power for an
existing automobile can be of low enough weight and size, and have
sufficient response time to be indistinguishable from gasoline-powered
automobiles. ' They are very quiet, the fan and blower noise being
the largest contributor to noise; they are very smooth in any workable
configuration; they can be made to be very low-emissions engines,
they will have low fuel consumption, somewhere close to a nonemission-
controlled diesel engine; and they can have exceptional life. On
the other hand, the radiator will be harder to fit into a standard
automobile. * Cost and production problems have not been resolved
so that the present cost projections show competitive values to diesel}
but not to spark-ignition, engines.
Predicted emissions were reported in Reference 116 and still
apply. No direct measurements with Stirling engine-equipped cars have
u j i_ . - u TJ u i 169-172
been made. However, the emissions should be very low.
It is also apparent that the present developers feel that they
are at the threshold of the next steps in dramatic improvement. *
171,173,174 - . , . , _ ... 166 .
These involve incorporating cheaper materials, improving
the power control system to be cheaper and more efficient, 3 and
more completely integrating the engine into the power train to better
meet the driver's demands. They are now better able to cope with
optimizing for different applications such as automobile duty, medium
duty, and heavy duty- Much remains to be done, and at present rates
of spending (about 230-men average Load over the world), it will still
be three to four years before an acceptable automobile engine will be
in existence.
The Stirling engine must still be regarded as an experimental
engine for automobiles. While the basic engine is understood, there
are a large number of design compromises needed (and unsettled at
-------
195
this time) before the proper development direction can be chosen for
particular applications. For instance, it is known that fully
metallic engines can be of high efficiency iind be quite small and
light, but they are expensive. On the other hand, ceramic parts
should fit very well into several places of the Stirling engines.
This should ultimately lead to inexpensive engines. However, it is
not clear which parts will be cost effective to switch to ceramics
in mass production, there are no suitable ceramics in mass production
for use in such applications, design compromise to use ceramics in
such engines is just starting to be a known art, and efficiency
versus size of Stirling engines as affected by ceramics is not yet
assimilated into the technology. The ceramic work being done on
behalf of gas turbines can also be applied to Stirling engines.
a. Stirling engine^ characteristics -•- The objectives for design
of a workable Stirling engine beyond that required for any positive
displacement engine, primarily are as follows;
prevent fluid leakage from inside the loop to the outside
past the power shaft or rod to keep the engine operable;
keep all volumes outside the swept volumes as small as
possible for highest specific power density;
minimize pressure losses as the fluid moves back and forth
through the heater, regenerator, and cooler for high
efficiency and greatest power control range;
handle as much fluid as possible for best specific
power density;
operate at as high a peak temperature as possible for
high efficiency;
prevent loss of heat from the hot side to the cold side for
high efficiency.
-------
196
These translate into a requirement to use pressurized hydrogen or
helium as the working fluid. The classic problems of Stirling
engines that also arise from the above list of requirements are;
(1) Heater head:
Requirements are small volume, large area, low fluid
pressure losses, high-temperature materials. Usually
forces the use of H or He under high pressure as
the working fluid;
Makes thermal stress a severe problem;
Makes for high-cost materials and construction
technique.
(2) External seal and working fluid diffusion losses:
Requires either very low loss so one charge lasts a
tolerable time without power loss, or requires that
the engine be rechargeable.
A third classic problem arises when consideration is given
to changing power level:
(3) Power control:
Requires very rapid method of changing fluid quantity
and/or method of changing pressure amplitude variation
with a fixed-fluid quantity, to be workable at any
engine speed.
All of these problems contribute to the potential cost.
Practically all of the development work going on at this
time, beyond making the engines operable in automobiles, is toward
technologically suitable solutions of the three major technical
problems. Designs which appear suitable for lowered cost are to be
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197
developed later from these solutions, so that lower engine costs
follow by normal cost reducing methods. One developer is aiming for
a car installation that will have run a total of 50,000 miles by
December 1975.
It is worth noting that the safety of automobiles has
been checked when the hydrogen-working fluid inventory has been lost
into the engine compartment. No significant hazard appears to exist.
b. Future possibilities — It is apparent that much ingenuity
has yet to be expended on heater-head design. This thinking is being
tempered by the great desire to incorporate ceramics into many parts
of the design for very high-performance engines. However, the only
ceramic part in any existing automobile-type engines actually
running is the rotary air preheater. Time limitations imposed by
the automobile company contracting for Stirling engines (Ford)
have precluded including extensive development work in ceramics at
this time.
The control situation is till pregnant with concepts yet
to be tried. The ones being used presently are the variable-mean-
pressure type, and the variable-pressure-amplitude type. A
simplified variable-amplitude type makes use of fewer valves, with a
goal of simplifying to one set of valves for control of all chambers.
Philips is reconsidering the variable-pressure control to see if it
can be improved. MAN is working on a proprietary system that would
bypass the major drawbacks of the variable-amplitude and variable-
pressure systems.
Sealing appears to be a tractable problem, more in that it
be designed around, as well as partially solved by5 direct attack.
United Stirling uses a sliding seal with provision for onboard
hydrogen makeup. Yearly leakage of a 100 hp engine would be about
4 Ib of hydrogen based on their existing data (about 100 refills
per year). Philips uses the roll-sock seal for stopping leakage
-------
198
at the seal, and only a yearly check of hydrogen inventory Is needed,
The prime movers are all presently piston-type, positive-
displacement devices. At least one patent has been issued to an
auto company for use of rotary positive-displacement devices. Assuming
the mechanical seal problem associated with such configurations can
be solved, development could lead to an engine of small overall
prime mover size simply because the drive mechanism would now be
better incorporated into the package design. The largest part of
the prime mover sections of existing Stirling engines is the drive
mechanism, be it rhombic drive, connecting rods and drive shaft,
or swash plate. A V-4 engine is fitted into the Pinto, and a swash
plate engine is being fitted into the Torino (Philips 4-215 engine).
One additional concept worth noting is that one developer
thinks highly of a method that incorporates a variable swash plate
165
into the drive design that would essentially eliminate the transmission,
The Stirling engine leads itself well to operation with stored
head. The engine can be combined with a thermal storage system
(thermal battery) to operate either with sensible heat, heat of
fusion, or both, depending on the heat storage material. One research
group believes that small cars using Stirling, engines with thermal
l65'
storage units are practical for urban driving. Projected heat
storage capacity using fluoride or eutectics of fluorides at
550-S60°C range from 0,33 to 0.47 fcwhr per kg or 0.72 to 0,93 kwhr/dm,
About 35% of this is deliverable as mechanical energy. The delivered
energy density would be 50 to 70 whr/lb compared to about 10 to 12
whr/lb for the best existing lead-acid traction batteries. This
system would be a competitor to the small battery-powered urban car.
The BTU energy balance favors the battery system, but the thermal
system can be lighter. Costs of the thermal system are not yet
worked out.
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199
12.5 Reciprocating Brayton-Cycle Engines
These engines use reciprocating parts to accomplish compression
and expansion. The cycle is basically the same as for gas turbines,
and all of the thermodynamic options open to gas turbines are open
to reciprocating Brayton engines:
1) Air working fluid, with heat recovery, internal firing
2) Air working fluid, with heat recovery} external firing
3) Air working fluid, no heat recovery, internal firing
4) Air working fluid, with heat recovery, external firing
5) H or He working fluid, with heat recovery, external firing.
Only the last one has been studied experimentally in the last few
years; types 3 and 4 have been in the patent literature for decades.
Thermodynamic performance demonstrated to date on Type 5 is quite
poor (about 12%)} but an efficiency on the order of 2770-30% should
be attainable using the same materials, etc., that would be used in
176,177
the equivalent Stirling engine. The Brayton engine has the
advantage that pressure losses due to small heat exchangers can be
avoided and that power density is not sensitive to external volumes,
But, it has the disadvantage that one set of hot valves is needed,
Otherwise, the Stirling engine and externally fired Brayton engine
with H or He working fluid have many of the same characteristics.
The Brayton engine has some design flexibility advantage over the
Stirling engine in that more freedom on pressure ratios exists. This
may be an academic advantage, however, since present Stirling volume
ratios appear near optimum. Because the Brayton engine relies on
isentropic processes for compression and expansion instead of iso-
thermal heat transfer processes (as in Stirling), and because the
Brayton engine uses a recuperator rather than a regenerator (as in
the Stirling) for cycle heat recovery, the Brayton engine thermodynamic
efficiency runs somewhat lower than for a Stirling engine operating
-------
200
the same temperatures. A recuperator transfers heat between
two fluid streams with an effectiveness of 8570 or less except where
large volumes can be tolerated. A regenerator collects heat from a
hot fluid, stores it, and Later transfers it to a colder fluid with
effectiveness that can range up to 98%. The meaning of these trade-
offs is that the Stirling engine should be able to attain higher
efficiency at the same or less cost, but that the design problems are
more difficult than for the reciprocating Brayton cycle.
The use of air in reciprocating Brayton engines is possible
from a practical point of view because the heat exchangers can be
designed for air without compromising the engine power density and
efficiency. The operating conditions of the engine are limited,
however, by the action of hot air on the materials of construction.
Whether internally or externally fired the same limitations apply.
Internal firing has the advantage of reducing heater size and cost,
but could Lead to poor emissions if the performance is to be
satisfactory. External firing has the same limitations as for the
H. or He engines.
If the problems associated with achieving a suitable Stirling
engine design of the conventional type prove insurmountable from a
cost point of view, then the reciprocating, valved, Brayton engines
will be worthy of further consideration,
12.6 Flywheel Systems
FLywheeLs of new designs offer the possibility of very high
178,179
energy storage density. A flywheel with sufficient specific
storage capacity to drive a car in a conventional way requires a
sophisticated design, a vacuum chamber to run in, and a seal and
vacuum pump for maintaining the vacuum. The drive requires an
alternator with a variable-speed, variable-frequency type converter
or variable-speed, constant-frequency converter with additional
-------
201
control for electrical drive or an Infinitely variable transmission,
Thus>for the electrical drive, the drive system alone will cost
one and one-half to two times the engine and transmission it replaces.
174
This is the same as for battery-drive vehicles. In addition, there
is the cost of the flywheel assembly. Unlike battery drives, there
is little probability that the flywheel could be an easily replaceable
unit for quick change at a service station. Thus, the flywheel has
to be considered part of the automobile's first cost to the customer
rather than an operating cost as with gasoline or easily replaceable
batteries. Flywheels and their vacuum chambers suitable for 200-250
mile range will probably cost on the order of an uncontrolled engine,
sized for similar service, based on estimates available in preliminary
studies. Special transmissions, vacuum devices, chargers and
controls, or electrical drives are additional. Also, the demonstration
of such a system in an automobile, irrespective of cost, is several
years away.
Use of an infinitely variable transmission would bring the
power plant cost down to that of the flywheel assembly, the transmission,
a gearbox, and a charging motor. The total cost may conceivably be
brought down to one and one-half to two times that of uncontrolled
spark-ignition engines if the flywheel assembly can really be made to
cost the same as an uncontrolled spark-ignition engine. Demonstration
of this cost probability and demonstration of the flywheel system
in a vehicle would be required before it could be considered seriously
as an automobile drive. The safety aspects of flywheel operation
will also have to be demonstrated in a vehicle, although the frangible
flywheel using glass fibers has been shown to disintegrate effectively
without problem when malfunctions occurred. The emissions would take
on the nature of the central powerplant, similar to battery systems.
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202
12.7 Electrically Driven Vehicles
a. Introduction -- The assessment of the performance of present
and anticipated electrically driven vehicles as presented in Reference 116
requires additions and corrections in the light of new developments.
Recent vehicle systems studies, battery and vehicle test pro-
186-189 , . , , , 190-194 _
grains and advancements in battery technology allow a more
concrete appraisal of future vehicle capabilities. The gasoline fuel
shortage experienced during the past year, as well as the rapidly rising
cost of crude oil, have provided a powerful spur for seeking alternative
power sources for transportation. Electric vehicles, at least on super-
ficial examination, seem to offer potentially significant fuel savings.
(183,188,195,196)
It is well understood, of course, that the use of electrical
drives in vehicles entirely removes the polluting source from the vehicle
and transfers it to the central power plant. The cleaning up of emis-
sions from power plants need not be considered here; this problem is
already receiving intensive attention. The additional power demand by
electric vehicles seems not serious considering the unavoidable low rate
at which such vehicles could be added to the present transportation
scheme. For instance, if all driving in the USA were by electric cars
12
(approximately 10 miles per year) requiring about 0.4 kwhr/mi, the
nighttime average electrical generating capacity required for charging
would be about 150,000 megawatts. This is not much greater than the
present nighttime excess generating capacity in the United States.
Gradual introduction of electrical vehicles should result in demands
less than the excess capacity.
b. Batteries -- Results of recent test programs and of develop-
mental efforts lead to the following assessment of present and future
capabilities of batteries:
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203
(1) The lead-acid battery is the only currently available
electric sotrage system for automotive traction with a reasonable cycle
life and cost per unit energy stored. Its key limitation, energy storage
density, can be improved sufficient (from 10 to 12 whr/lb to about 13
to 15 whr/lb) but this is not to permit application beyond rnarginal-
197
performance urban vehicles, delivery vans and busses. Even if the
cycle life were to be extended to 1,000 deep cycles, the amortization
of the battery over its lifetime will lead to a cost of the battery
i +-,.<** iu^i- j 180-182,184
alone amounting to 3-5 cents per kwh delivered.
(2) Other battery systems with "intermediate" performance
187 1 90
will very likely become available within the next five years; '
see Table 12.3, Although these promise to provide two-to-threefold
improvement in energy density ; relative to the lead-acid battery, it
is unlikely that their cycle life can be sufficiently improved to
provide economically attractive energy storage cost. However, because
the future Zn-NiOOH system may have good power capability, its applica-
tion in electric vehicles and perhaps in gasoline-electric or battery-
battery electric hybrids deserves consideration.
(3) Recent advancements in the technology of the solid
electrolyte (beta-alumina), as well as in other critical areas affecting
the feasibility of alkali metal sulfur systems, increase confidence
in the eventual technological feasibility of high-energy, high-power
182 192 195
density battery systems. ' ' Prototype producing and testing
programs should provide definitive answers in the next three to five
years as to whether the alkali-oetal-sulfur batteries can provide an
economically viable solution to the energy storage needs of electric
vehicles. Indications at present (Table 12.3) are that battery
amortization costs may achieve a level below I/cent/mile, Current
work on the feasibility of battery schemes employing alkali-metal
-------
TABLE 12,3
Batteries for Electrically Driven Vehicles
System
Pb/H..SO ,/PbO *
7,n/KO!l,'KiOOH
Zn/Z«a2/Cl2.6H20
Fc/KOH/NiOOH
H /KOH/NIOQH
2
Li/LiCl.KCl/S
Li,Al/LiCl,KCl/FeS2
B-Alumlna
Na or S
Na— glass
Theoretical
whr/k§_
175
326
465
267
381
2,500
790
760
Best Present
Performance
wh/kg
22
to
26
55
70
36
65
150
120
90
peak
w/kg
100
to
^00
loo*-*
to
200
50
35
40
150
120
150
cycle
life
300
to
1,000
200
10
2,000
1,000
100
200
1,500
operating cost
timejyear §/kWh
1.5 30
to to
2 50
1 100
? ?
3 50
1 ?
0,2 ?
0,5 1
1 ">.
wh/kg
28
to
33
30**
to
35
110
44
80
330
200
180
peak
_ w/kg
100
to
.100
100**
to
200
100
100**
to
200
100
200
200
200
Anticipated
Performance
cycle
life
500
to
1,000
500**
500
500
3,000
1,000
1,000
1,000
operating
t line ,y ear
3
3
3
5
3
3
3
3
cost
$/kwh
40
to
50
30*| ,
tcr '
50
50
50
(1)
100
(1)
20
50
20
50
20
50
year
1976/
to
1978
1978*/
to
1980
I960
1978
1980
1980
~Data and estimates pertain to deep (70-807=) discharge at 1-3 hr rate. Range of numbers refer to range of usage.
--••Ranges refer to uncertainty.
(1) With metal recovery accounted for.
-------
205
negative electrodes at lover temperatures (in the range of 200 C)
190
shows good initial promise. Significant advantages in cell
construction technology and cost may be derived from operation at
this lower temperature level. Production of significant numbers of
electric vehicles based on alkali metal batteries cannot be expected
before 1985 at best,
c. Electric drive train -- There are a number of viable
alternatives for motor and switch-gear systems suitable for use in
electric vehicles. Systems studies and experimental test programs
indicate that electric systems which have favorable torque and
speed-control characteristics combined with high efficiency will have
initial costs (excluding the battery) comparable to or higher than the
L , 182,183,185
present-day drive train or gasoline-powered automobiles.
Weight of the drive train depends greatly on the systems although
the order of magnitude appears to be about 1% to 2 kg/hp. The VW
van being worked on at DAUG and VW suffers a weight penalty of about
100 to 200 Ibs for an electric vehicle without batteries compared to
a gasoline-engine-powered van. Motor and switch gear possessing
optimal characteristics for electrics are not yet fully developed.
The drive train aspect of electric vehicles, however, does not appear
to present the limiting factor in the eventual realization of
efficiency and economically attractive electrical vehicles.
d. Hybrids -- Recent tests by EPA on a gasoline-engine-battery-
198
hybrid vehicle (Petro Electric) demonstrated with a 43QQO Ifa vehicle
the following emissions and fuel economy over the Federal Driving
Cycle:
HC CO NO MPG (avg) MPG (engine off at idle)
x
(grams per mile)
0.45 2.08 0,90-1.14 10.4 12.4
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206
A Wankel engine and lead-acid batteries were used. The driveability
of this vehicle was acceptable. Further improvements in meeting emis-
sions standards and in gas economy can be expected by using a conventional
small gasoline engine rather than the Wankel employed in this test vehicle,
•j Q t "I fi7
Other test programs involving hybrids ' have not produced as yet suf-
ficient data on emissions characteristics and on energy efficiency to
make meaningful conclusions possible. Because hybrid drive systems are
more complex than either of the derivative systems, the initial cost of
the vehicle promises to be high. However, the anticipated longer cycle
life of advanced battery systems may provide a basis for favorable
vehicle cost per mile.
Tests conducted at EPA in October-November of 1974 with the
Petro-Electric vehicle yielded the following results:
HC 0.38 g/mi
CO 2.41 g/mi
HOX 0.76 g/mi
MPG 9 urban
16 highway
These results were obtained at 4,000 Ib inertia weight and with a high
rear-end ratio. The mileage is for the battery recharged to its
starting level. A rotary engine is used in conjunction with the elec-
tric system. Using an EPA determination factor for a rear-end ratio one
half that used in the test, and the improved economy of a piston engine
versus a rotary engine, the predicted urban mileage would be 1.35 x 2* x
measured value =17.9 mpg. Past EPA tests on the Petro-Electric vehicle
have indicated highway mileage nearly double the urban mileage.
The electric system includes a set of starter, light, and ignition
(SLI) batteries having 90 amp hours of storage. Discharge is only by
2 amp hours before recharging starts and does not normally exceed 6 amp
hours during operation. Also included is an electric motor rated at
10 hp continuous, or 20 hp for one minute, or 40 hp for acceleration.
Telephone call from H. Wouk, President^ Petro-Electric Motors, Ltd,
to J. Bjerklie, December 12, 1974.
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207
Costs have been resolved except for the batteries and the motor In
large production. Including these items, the purchase cost of Lhe Petro-
Electric vehicle would be between 1070-20% higher than the equivalent
gasoline-engine-powered vehicle for the same emissions and performance.
(Note; This information was approved and added to the consultant report
December 13, 1974.)
(e) Power demand -- Most recent estimates on power demand ' " *
196 199
3 to be created by electric vehicles tend to confirm earlier esti-
mates according to which the availability of centrally generated electri-
cal power and of distribution network is not likely to present a constraint
on the introduction of even a moderately large population (i.e., addition
of 1-2 million vehicles/year) of such vehicles. Because of the load
leveling potential of electric vehicles (i.e., charging during off-peak
periods), economical benefits may be derived from such a power demand
196
resulting in lowering the average cost of power. In the planning of
central load leveling facilities, it would be of distinct advantage to be
able to rely on competent estimates regarding the expected penetration of
electric vehicles in the transportation system.
(f) Energy economy -- The energy requirement of an electrically
driven vehicle compared to that of a gasoline-driven car has been
u j 180-184,188,195,196,199 „ _
estimated by a variety of methods. Because of
the paucity of road-test data on electrics, a fully reliable comparison
is still not available. One of the key difficulties In making a valid
comparison between even the smallest gasoline-driven automobile and an
electric vehicle available for road tests is that at present the only
battery system (i.e., the lead acid) at all suitable for vehicular
application provides extremely limited power and range. Once we put
together on paper an electric car with performance similar to at least
the smallest cars on the road today (Honda, Pinto, Vega, VW, etc.),
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208
we must anticipate performance of batteries which are not yet
available.
Keeping the foregoing remarks in mind, recent system-performance
studies provide the following estimates:
The energy requirements per mile of lead-acid-driven electrics
using current technology for the frame and driving train are comparable
TOO 1QA
to the subcompacts on the road today ' (0.25 to 0.5 kwhr/mile).
This disappointing performance results from the very high weight of the
battery required for even a marginal vehicle range and marginal accelera-
tion/hill-climbing capability.
The energy requirements per mile for cars powered by "intermediate"-
type batteries (e.g., NiOOH, Ni-H7) can be expected to be comparable to
those of current subcompacts. The higher energy density and power density
of these intermediate battery types will considerably reduce vehicle weight.
The energy requirement of electrics using alkali metal-sulfur
batteries, with energy and power densities in the range of 100 kwh/lb and
100 wh/lb,, respectively, should be somewhat lower than present-day,
gasoline-driven vehicles (compacts) with comparable performance.
It is worthwhile to compare the amount of raw fuel required
per mile to drive electric and heat-engine-powered vehicles. From
the results indicated above, it can be assumed that electric cars com-
petitive to subcompact gasoline cars will require an average of about
0.35 kwhr/mile. On the other hand, a family-size car averaging 15 mi/
gal requires about 0.45 kwhr/mile. This would correspond to an intermediate-
size car powered by a Stirling engine. The conversion of raw fuel to
drive-shaft power would be approximately as follows:
-------
209
Electric Car Heat Engine
Fuel processing efficiency = ,9 .9
Power plant efficiency = .32 .19
Trnasmission line efficiency = .91
Battery charge/discharge efficiency = .7
Motor/control efficiency = »8
Transmission and gear = .9
Overall efficiency = .146 .154
Adjusting for the difference in kwhr/mile required by the two modes
of transport, the ratio of electric vehicle to heat engine vehicle
fossil fuel requirements is 0,82. This ratio is low enough to induce
some interest in electric vehicles at the present time.
If the transportable fuel of the future requires more
thermal or electrical processing than indicated above, the energy
ratio will drop further since the fuel processing efficiency for
electrical generating plants need not change so long as fossil fuels
are used. For instance, if hydrogen were to be required for
automobile fuel in the future, and if it were to be generated
electrolytically, the ratio will be under 0,6. This should include
higher interest in electric cars if energy remains a potential major
national problem.
-------
210
g, Summary:
(L) There are no alternative engines that can be available
in mass production for automobiles of standard size
and performance before the 1980's.
(2) All of the alternative heat engines can be made to
meet the 1978 emissions standards} with Stirling
engines and steam engines able to do so most easily
and with least controversy on interpretation.
(3) Present gas turbines show poor fuel economy in urban
driving, but could be made to show good characteristics
for touring-type driving.
(4) High-temperature gas turbines with ceramic components
for high-temperature portions of the engine should be
technically competitive with spark-ignition engines
over 50 hp and should demonstrate excellent fuel
economy over a Federal Driving cycle. Their economic
competitiveness is not now clear.
(5) Stirling engines should ultimately be technically
competitive with spark-ignition engines over the
power spectrum used by conventional automobiles.
It is a necessary, but not sufficient, condition to
achieve a control system and heater head that can be
made at a considerably lower cost than at present
to be economically competitive.
(6) Steam engines have been shown to be technically suitable
as an exhaust-clean engine for powering lightweight
cars.
-------
211
(7) None of the alternative heat engines have been shown
to be suitable in the hands of the public, although
gas turbines come closet to having done so.
(8) None of the alternative heat engines have been shown
conclusively to have a suitable cost structure for use
in conventional automobiles,
(9) Light vehicles powered by efficient, externally heated
engines (such as Stirling), using heat stored in a
thermal storage system,, are being studied for their
suitability as an urban vehicle. The system has not
yet been shown to be economically competitive.
(10) Heat engine-battery hybrids have beem demonstrated
successfully at the EPA to achieve on the Federal
Driving Cycle; EC = 0.45 g/mi, CO = 2.08 g/mi and
NO = 0.9 to 1.14 g/mi, and to negotiate the Federal
X
Qriving Cycle successfully,
(11) Flywheel systems have not been shown to be competitive
with spark-ignition engines costwise, technically,
or for overall emissions,
(12) Based on present technology, it is feasible to
manufacture electrically driven personal vehicles for
restriced (low range and power) urban use. These
vehicles, even when equipped with the best, currently
available, lead-acid storage batteries, will have
significantly higher initial cost and vehicle cost
per mile than today's gasoline-driven subcompacts
with no improvement in overall energy efficiency.
-------
212
(13) Active development programs exist for battery-powered
delivery vans and urbans Susses. Their duty cycle
offers an opportunity that is thought may prove
economically viable for the introduction of electric
drives and lead-acid batteries.
(14) By substantially increasing the cycle life of lead-acid
batteries, major improvements in energy economy and
vehicle cost per mile may be achieved by decreasing
the cost per mile of the battery. Significant
improvement in range is not likely to be achieved
with the lead-acid battery,
(15) Other battery types currently in advanced development
stage (e.g., Zn-NiOOH, H -NiOOH) may be expected
within five years to provide approximately twice as
high specific energy (range) and significantly improved
power capability compared to the current best lead-acid
system.
(16) The high energy and power density alkali metal-sulfur
batteries currently under development show good promise
and should reach advanced testing stage in two to
three years.
(17) In view of the strong likelihood for a gradual shift
toward coal-nuclear-geothermal and, perhaps, solar
primary energy sources, there are incentives for the
development of advanced storage batteries for
electrically driven vehicles,
(18) A summary of fuel economy data for alternative engines
is given in Figure 12.3.
-------
o
~z.
o
30
20
10
Ceramic Turbine
(projected)
- 2500 F
51 Data-EPA
Other—As Noted
Emission Capability
• Steam \ ng7g Std; ,
D Stirling {
\ 1978 Stds.-Variable
O Gas Turbine ^ 2 g/mi N0^_.Fixed Combustion
A Electric-Heat Engine Hybrid
(1975 Stds.)
Phillips (predicted!
Iprojectedl
SES (predicted!
O
Williams Res.
lapprox.)
SEPA-1974 Spark Ignition
I Engines
0
2000
3000
4000
VEHICLE WEIGHT (Ib)
5000
6000
FIGURE 12.3 Fuel Economy - Alternative Engines, All Data Are Measured
Except: Predicted from Dynamometer and Projected from Extrapolation,
-------
13. ALTERNATIVE FUELS
13.1 Introduction
The recent gasoline shortage in the United States has served
to emphasize the critical dependence of our transportation system on
a readily available and abundant supply of gasoline. Nearly all
present-day transportation systems are powered by petroleam-derived
fuels. Petroleum currently supplies almost 507o of U.S. energy needs
•with the transportation sector, in turn, consuming about half the
petroleum. Gasoline for automotive consumption represents
approximately 75% of this transportation fuel demand, or nearly 20%
of the total U.S. energy usage. It is not surprising then that
alternative fuels for automobiles are of great current interest in
view of government plans to try to reduce the petroleum dependency
of the United States.
The subject of alternative fuels interacts in various ways with
the current Committee on Motor Vehicles study. First, and most
obvious, the types of fuels available can potentially have a
significant effect on the performance, efficiency and emissions
characteristics of the various automotive power sources being
considered. Thus, an attempt is made here to identify the alternative
fuels that may become available in the future,
The type of fuels which will be available will, in turn, depend
upon the future energy supply spectrum. National policy concerning
this future energy mix is currently being formulated in terms of
research and development goals and budgets for nuclear. coal, oil shale
and other energy sources. The identification of those synthetic fuels
which are most attractive for automotive applications should serve as
input to these energy policy decisions. Those alternative fuels
particularly advantageous for automotive use are identified and
discussed in the present study.
Another motivation for considering alternative fuels is the
interaction between alternative fuels and alternative power plants.
214
-------
215
Many of the alternative power plants are chacterized by continuous-
combustion systems with relatively little fuel sensitivity, while
other power plants may require fuels with specific octane or cetane
ratings. The future availability of fuels of various types may then
affect decisions regarding production of automotive power plants
of a given design. The spectrum of available fuels may also affect
the design of conventional spark-ignited engines, stratified-charge
engines and diesel engines, and discussion of alternative fuels
for these engines is included here.
For the present study, alternative fuels are defined as those
fuels not derived from the normal petroleum base. Fuels which are
derived from such sources as coal, oil shale, natural gas or nuclear
energy resources are considered. Except for direct use of natural
gas, all of these energy sources require further synthesis or
conversion to obtain a form suitable for automotive application.
Hence, the term "synthetic fuel" can also be used to characterize
fuels from these resources. In the cases where the alternative fuels
are synthetic gasoline or synthetic distillates, the discussion
includes information on their potential availability and cost, but does
not dwell on their application to conventional vehicles.
The objective of this study is to assess the potential for
alternative automotive fuels from the standpoint of energy supply
and cost, vehicle efficiency, performance and emissions. Also,
where possible, an attempt is made to assess the time frame for
availability of the various synthetic fuels.
A summary of synthetic fuel cost and supply data based on
presently available estimates is given in the next section. Subsequent
sections contain detailed assessments of the prime non-conventional
synthetic fuel candidates: hydrogen, methanol and gasoline-methanol
blends. A discussion of systems employing reformed fuel is also
included because these systems have potential fuel economy and
emissions advantages.
-------
216
13.2 Candidates, Costs and Time Scales
Given the energy resource picture for Che United States
and the projections for rates of energy usage, it quickly becomes
apparent that a heavy reliance on imported petroleum can only be
avoided by exploitation of non-petroleum, domestic energy resources.
A typical petroleum demand projection is shown in Figure 13.1, taken
from Reference 200 and indicates that petroleum demand due to
transportation alone will outstrip domestic supplies by 1980.
It is of interest then to consider the possibility of using
non-petroleum energy resources for synthetic fuel production for
automotive transportation needs. The available major domestic
energy resources in this category include coal, oil shale and
nuclear supplies. Solar and geothermal energy resources may also
enter the picture, but detailed analyses of their application to
synthetic fuel production are not readily available. Foreign
natural gas is the other non-petroleum resource considered here.
Given these energy resources, fuel candidates, costs and availability
are analyzed in this section.
Recent studies performed for the Environmental Protection
201 202
Agency by the Institute of Gas Technology (1GT) 3 and Exxon
203
Research and Engineering have identified alternative automotive
fuel candidates and costs based on use of domestic resources. While
both studies started with a long list of possible fuels, many were
immediately eliminated for obvious hazard, availability, storability
or cost problems. The IGT study provided cost data for a number
of fuels, while the Exxon analysis eliminated all but a few
candidates for practical reasons before final cost Bata was completed.
Cost estimates from these studies in 1973 dollars per million Btu
at the pump are shown in Tables 13.la and 13.Ib. Current gasoline
prices (without taxes) are equivalent to about $3.50/10 Btu.
-------
217
10
9
Cumulative ot! consumption
(109bbl) 108
Approximate _
total energy
210
|
Total demand f \
V /, / Electric utilities
\^/ <
^,jK"-y j
/:%1
^^:; N
'v;XvX'x'i > Industrial
•-f~-' O- -. ••! i
ransportation
(60 X 109 bbl)
Trinsportation
1960 1§70
YEAR
1980
1990
FIGURE 13.1 U.S. Petroleuci Supply and Demand (Including
Natural Gas Liquids),
Source: Reference 200
-------
218
TABLE 13, la
Cost of Alternative Fuels
Cost at Pump
Resource Base Synthetic Fuel $10/6 Btu. __
Coal Gasoline 3.00 (+1,70)
Distillate 2.65 *<+1«
Methanol 2.85 (+2.38)
Liquid SNG 3.60 (+0.94)
Liquid H2 5.65
H2-Hydride 3.55
*Co- product ion (50-50) gasoline and distillate
Oil Shale Gasoline 2.95 (+1.20)
Distillate 2.50 (+1.20)
Nuclear Energy Electrolytic H
Liquid HZ 7,60
H -Hydride 5.50
Thermochemical H
Liquid H 6.10
H -Hydride 4.00
A s s_umj3 I: ions :
Costs are in late 1973 dollars, for investor financing with
approximately 10% DCF. Capital and operating costs were based on
published (late 1960's) costs and are probably somewhat optimistic.
No te :
IGT has recently completed more detailed cost analyses for
several of the above fuels. These costs were based on full-size
plants reflecting maximum economy of scale. Costs included total
plant investment, 1070 overhead, 157, contingency, interest during
construction, start-up costs and operating costs. Substnatially
greater production costs were obtained in this analysis. Increases
are shown in the figures in parenthesis above (Ref. 2a).
RBF 201
-------
219
TABLE 13.Ib
Cost of Alternative Fuels
Cost at Pump
Resource Base Synthetic Fuel $/10 Btu
Coal Gasoline 3.35
Distillate* 2.75
Methanol 3.85
Oil Shale Gasoline 2.65
Distillate* 2.05
^Produced as coproduct with gasoline
Assumptions:
1973 Dollars, 10% DCF Return.
REF 203
-------
220
204
Jaffe e t a 1 . have estimated selling prices for methanol from
coal for a number of coal sources and gasification processes. Their
results for methanol from coal, without coproduct, are in the range
$250-$3. 00/10 Btu for investor financing at 127, DCF. Transportation
charges (about $1.50) would have to be added to these costs to arrive
at a cost.
Other estimates for methanol costs are also available. Vulcan-
Cincinnati Company estimates that methyl fuel (methanol with small
amounts of high alcohols) could be produced from coal for $1,02/10 Btu.
Dutkiewicz estimates that methanol produced from natural gas in the
Middle East could be brought to the United States for $1.05/10 Btu.
202 203
Transmission and distribution would add about $1.50 to these costs *
for an estimated total delivered methanol cost of $2.50/10 Btu.
The time frame for availability of the various synthetic fuels
is also of interest. The Office of Coal Research (OCR) estimates that
the data necessary for design of a commerical-size plant for substitute
207
natural gas (SNG) production from coal will be available by 1980.
However, due to increasing demand for natural gas in present markets,
it is unlikely that SNG from coal would be available for automotive use
202
any time before 2000, if then. The state of the art in coal lique-
faction in the United States is not as advanced as coal gasification,
OCR estimates that the technology for pilot and demonstration plants for
207
liquid fuels from coal should become available in the early 1980's.
Allowing time for demonstration plant operation, synthetic liquids
(gasoline and distillates) from coal will probably not be available in
substantial quantity before the late 1980's.
Production of methanol or methane and methanol is another
possible option for coal gasification plants. This would involve
-------
221
first producing synthesis gas (containing large quantities of CO and
H ) in much the same way as in SNG production, Methanol would then
be produced from the synthesis gas by commercially available catalytic
conversion methods. This would have the advantage of producing a
liquid fuel from coal while requiring only gasification technology
rather than direct liquefaction technology. An early 1980's time
frame is then probably appropriate for methanol from coal. Mills
208
and Harney have discussed methanol production from coal and
suggest a production cost in the range of $1.00-$1.20/10 Btu, Methanol
is currently produced via steam reforming of natural gas, and it has
been suggested that natural gas from the Middle East be converted
206
to methanol for shipment to the United States. No further
technological development would be required here.
Production of gasoline and distillates from oil shale is also
an attractive low-cost option (Tables 13. la, 13.Ib). Oil shale
leases have recently been granted and processing plants are being
designed. The technology for retorting the shale oil to a synthetic
crude oil is known, and a few plants based on ~urface mining of shale
209
will probably be in operation in the early 1980's. The major
limitations here are not technology development or processing costs,
but enviornmental problems and water shortages which may limit
the scale of operation.
Cost estimates for either liquid or metal hydride forms of
hydrogen are relatively high (Tables 13.la, 13.Ib) due to inefficiencies
in the electrolytic or thermochemical production methods and the
additional costs for either liquefaction or hydride formation.
Electrolytic hydrogen production followed by liquefaction is a currently
available technology, and development of more efficient electrolyzers
continues. Thermochemical hydrogen production and metal hydride
storage systems are still in the early stages of development and
may not be commercially available until the late 1980's. Although
-------
222
production of gaseous hydrogen may be relatively cheap (Tables 13.la,
13.Ib), its low density eliminates it as an automotive fuel.
Given the above cost and availability estimates, we identify
the most attractive alternative fuels as follows. Some quantities
of methanol from either coal gasification or foreign natural gas will
probably be available as early as 1980, If system studies indicate
that this fuel should be used in the transportation sector, then use
of gasoline-methanol blends for automobiles would be an early
application. Larger-scale production of methanol in the late 1980fs
could result in some use of methanol itself as an automotive fuel.
The most likely synthetic fuels for the late 19SO!s and the 1990 !s
appear to be synthetic gasoline and distillates from coal or oil
shale resources. Hydrogen may appear as an automotive fuel, but will
probably not be widely used before 2000.
A more detailed discussion of the automotive application of
several synthetic fuels is included in the following subsections. No
further discussion of synthetic gasoline or distillates is given since
these would be essentially the same as presently available fuels.
Systems which include on-board reformers are also discussed since,
even though the vehicle may be fueled with conventional fuels, the
engine will operate with some portion of synthesized fuel.
13.3 Hydrogen
During the past few years, hydrogen has received a great deal
of attention as a potential energy carrier of the future. Its major
attractions include the absence of carbon in the fuel and the vast
availability of hydrogen in water. The prime energy sources in
a hydrogen-energy economy would be nuclear, solar or geothermal,
and the hydrogen produced from these resources would serve the need
for an easily transmitted, storable, portable energy carrier. While
the beginning of any conversion to a hydrogen economy appears to
-------
223
be at least 25 years away, many investigations of hydrogen's potential
as an automotive fuel have already been carried out. The present
section discusses vehicular storage problems and potential automotive
engine performance and emissions with hydrogen as a fuel,
Assuming widespread production and distribution of hydrogen
as a multi-purpose energy carrier, the major problem accompanying
its use as a vehicular fuel is the requirement for on-board fuel
storage. The low volumetric energy density of hydrogen eliminates
gaseous storage and leaves cryogenic liquid hydrogen or solid metal
hydride compounds as possible storage modes. Cryogenic hydrogen
storage systems would occupy four to five times the volume of present
gasoline tanks, and would require a vacuum-jacketed, specially
200 213
insulted tank to minimize boil-off losses. * At the present
time, such cryogenic storage systems would be quite costly, although
large-scale mass production should reduce costs considerably. All
of this supposes a method for liquid-hydrogen delivery to individual
vehicles. Gaseous pipelines to service stations with liquefaction
equipment or widespread distribution of liquid hydrogen would be
required.
Metal hydride storage involves the formation of a solid phase
metal-hydrogen chemical compound, e.g., Mg H . Although the weight
fraction of hydrogen in these compounds is usually less than 5%,
quite high hydrogen storage densities can be achieved by virtue
of the solid phase. Magnesium or magnesium-nickel hydride systems
are estimated to weigh 600-700 Ib to give an energy storage equivalent
, 200,210
to a standard gasoline tank Iron-titanium or magnesium-iron-
titanium hydrides have operating temperatures and hydrogen evolution
rates more suitable for vehicular application, but would weigh as
211
much as 1,500 Ib. The metal hydride decomposition to give the
hydrogen fuel is an endothermic chemical reaction, and the vehicular
system would therefore require a provision for cold start-up and
-------
224
exhaust-heat recycle to deliver the fuel to the engine. Some
demonstration hydride storage systems have been built and laboratory
research programs continue to investigate lighter-weight metal
017
hydride compounds. Much of this research is being carried out
at Brookhaven National Laboratory. Widespread use of metal hydride
storage would^ of course, require a metal readily available in large
quantities. Hydrides can be recharged from a pressurized gaseous
hydrogen supply so that cryogenic distribution is not required.
While the vehicular storage of hydrogen requires some research
and development before widespread practical application is possible,
the efficient use of hydrogen in the vehicle power plant can be
accomplished with present-day technology. Hydrogen-air mixtures
are easily ignited and burn rapidly over a wide range of mixture
ratios. Alternative engines which employ continuous combustion
systems (Brayton, Rankine or Stirling engines) are thus readily
adaptable to hydrogen fuel. The primary combustion zone in these
systems can be operated much leaner than with hydrocarbon fuels so
that low nitric oxide emissions are easily attained.
Application of hydrogen to spark-ignited, reciprocating engines
requires some engine modifications for proper operation and some gain
in engine efficiency is possible. We mention here some recent
experimental results on the performance, emissions and special
problems of hydrogen-fueled, spark-ignited, reciprocating engines.
Since hydrogen-air mixtures require only one tenth the ignition
energy of gasoline-air mixtures, preignition and flashback can be
problems when operating with hydrogen. Both intake water injection
and exhaust gas recirculation (EGR) have been used to eliminate
these problems," ' Both of these techniques also reduce nitric
oxide emissions and maximum engine power, and water has the
additional complication of requiring a storage tank which must be
O t Q
freeze protected. Direct cylinder induction and high-pressure,
-------
225
direct-cylinder fuel injection ' have also been used to eliminate
flashback and preignition problems. Direct injection has a
supercharging effect and can increase power output 20% over a
carbureted system.
Engine knock is also a problem with hydrogen-fueled reciprocating
engines due to the high flame speeds of hydrogen air mixtures. To
avoid this, it has been found necessary to operate with mixtures much
leaner than stoichiometric or to employ EGR. Both of these
techniques result in some loss in maximum engine power,
A notable advantage of operation with hydrogen is the efficiency
gain attained through quality regulation of the engine power compared
with controlling output by throttling. This is possible because
of the extremely wide flammability limits of hydrogen-air mixtures
, , , , _ . . , , ,,. . 214,219
and has been shown to give increased engine efficiency.
Nitric oxide emissions with hydrogen fuel are affected by
engine variables in much the same way as with gasoline fuel. While
217 219
anomalously low emissions have been reported, * other
investigations have shown NO emissions to be similar to operation
214,215,220 x n J ,
with gasoline. NO control can be achieved by water
fi
injection or EGR as mentioned previously, and also by very lean
operation. Extremely low NO emissions can be obtained by restricting
X
equivalence ratios to one half or lessj although this then requires
214-220
a larger engine to achieve the same maximum power,
In summary, hydrogen is an attractive fuel from an emissions
and economy viewpoint and can be used to fuel conventional-type
engines. However, substantial development in vehicular storage
systems would be required for large-scale use of hydrogen. Such
large-scale use may be required beyond the year 2000 as fossil fuel
supplies are depleted.
-------
226
13.4 Methanol
Methyl alcohol (CH^OH), or methane!, has been identified as
a possible future synthetic fuel and has received considerable
attention recently. The present subsection discusses automotive use
of methanol fuel with respect to -vehicle performance and emissions.
Again, the continuous-combustion alternative engines are relatively
insensitive to fuel type and are easily designed for operation on
methanol. Thus, the discussion is mainly concerned with methanol-
fueled, spark-ignited reciprocating engines.
The use of alcohols as motor fuels is not a new idea. The
Society of Automotive Engineers held a special meeting on alochol
221 222
fuels 10 years ago and Bolt's survey presented at that meeting
refers to work dating back 50 years. The present discussion is not
a comprehensive review of alcohol fuels but rather a brief
evaulation of the principal operational, performance and emissions
characteristics of methanol-fueled reciprocating engines. Although
ethyl alcohol (ethanol) does not now appear to be a cost-effective
202
alternative fuel, much of the present technical discussion is
applicable to ethanol as well as methanol.
A comparison of the physical properties of methanol and
iso-octane is given in Table 13.2, taken from Reference 223. The
energy content per cubic food of stoichiometric methanol-air mixture
is about the same as with gasoline so that the engine power will be
similar.
One of the major problems associated with the' use of methanol
is fuel vaporization and distribution characteristics due to methanol's
relatively high heat of vaporization and large F/A ratios. Experimental
work with methanol indicates that specially designed carburetors
and intake manifolds will be required to provide the necessary fuel
222-225
evaporation and distribution. The high heat of vaporization
can, in principle, be advantageous in that it results in cooler
-------
227
TABLE 13.2
Physical Properties of Iso-octane and Methanol
Property
Chemical formula
Molecular weight
Specific gravity (68 F)
Stoichiometric A/F
Boiling temperature, F (K)
Latent Heat of vaporation at
B.P., Btu/lb (MJ/kg)
Heating value, Btu/lb (MJ/kg)
Higher
Lower
Energy, Btu/ft of Stoichiometric
mixture (1 atm, 60 F, LHV,
gaseous fuel) (MJ/nr*}
Same, liquid fuel
Octane No., Research
Octane No., Motor
Iso-octane
C8H18
114.22
0.692
15.1
211 (372)
117 (0.490)
20,556 (86.047)
19,065 (79.806)
95.5 (3.559)
96.6 (3.600)
100
100
Methanol
CH3OH
32.02
0.792
6,4
149 (338)
502 (2.101)
9770 (40.897)
8644 (36.184)
90.0 (3,354)
103.0 (3.839)
106
92
REF 223
-------
228
intake manifolds and better volumetric efficiencies as well as less
rj rj £"
compression work in the cylinder, "" The high heat of vaporization
also means that methanol-fueled vehicles cannoC be started in
environments below 50 F without the addition of a more volatile fuel
223-225
compound. The problem here is vaporization rather than
distribution, as indicated by tests where manifold injection of
9 o/
methanol did not improve cold-starting characteristics. It is
interesting to note that coal-derived methanol may contain small
225
amounts of higher alcohols which may help alleviate the cold-start
problem,
Performance, fuel economy and emissions with niethanol have also
, ^ . «.. „ ,223,225,226,228,229 „ ., . ,
been recently investigated ' 5 Both single-
cylinder-engine experiments and tests with properly carbureted and
manifolded-multieylinder engines indicate that the lean misfire limit
for methanol occurs at about 20% leaner mixtures than with gasoline.
Significant decreases in GO and HC emissions can be obtained by
operating with these leaner mixtures. Increased emissions of
aldehydes are generally observed along with some reduction in nitric
oxide emissions. The principal hydrocarbon emission is methanol,
which will be removed with water if an exhaust sample dryer is used.
The methanol response on FID analyzers has been found to be between
8070 and 100% of saturated hydrocarbon response. Performance and
fuel economy (on an energy basis) are generally found to be quite
similar to values obtained with gasoline. Since methanol has about
half the heating value of gasoline, methanol-fueled vehicles would
require twice as large fuel storage tanks for the range as
gasoline. A 1970 vehicle converted to methanol operation and equipped
with a special intake manifold and an exhaust-oxidation catalyst has
met the 1976-77 Federal Emissions Standards without specific NO
<-s <-> *\ X
2z3
control except lean carburetion. This vehicle did experience
severe cold-start problems until an ether injection system was installed.
-------
229
Corrosion of lead, magnesium or aluminum fuel tanks or tank
coatings has been identified as a severe problem in methanol fuel
226
systems. Corrosion of fuel-injector or carburetor parts can also
be a problem.
In summary, with respect to reciprocating engines, we find
that methanol is a suitable automotive fuel for the future providing
that the cold-start and F/A distribution requirements are included
in the engine design. This would require major redesign of existing
engine intake systems. Corrosion-resistant materials would have to
be used in vehicle fuel tanks and lines including parts of the fuel
injector or carburetor. Methanol appears to have the capability
for lower emissions (except for aldehydes) than gasoline, principally
due Lo the lower lean misfire limits, Methanol can be burned in
continuous-combustion-type engines with little or no difficulty as
long as a suitable start-up system is available.
13.5 Methanol-Gasoline Blends
Blends of gasoline with up to 251 methanol have been suggested
as gasoline "extenders'' for present-day vehicles and are currently
230
receiving increased attention as a result of recent fuel shortages.
Like pure methanol, methanol-gasoline blends have long been known as
potential fuels3 particularly for power boost in racing applications
where fuel injection and very rich mixtures are used. In this
subsection the fuel mixture and engine performance and emissions
characteristics of raethanol-gasoline blends are briefly reviewed
and assessed with respect to application to spark-ignited reciprocating
engines. As with most other alternative fuels, little or no problems
would be encountered burning these blends in continuous-combustion
engines.
Methanol added to gasoline has the effect of increasing the
-------
230
octane number of the fuel, although this point has been overemphasized.
While the research octane number (RON) of modern gasolines is increased
about four octane numbers (OH) by addition of 10% methanol, the more
severe motor octane number (MON) rating is only increased about 2 ON.
(226,231,232) Road octane numbers, which are measured in vehicle
tests, are found to be between the RON and MON values, and 10%
226
methanol in unleaded gasoline gives about a 3 ON boost here.
Fuel, volatility is also affected by mixing methanol with
gasoline. Distillation tests show a more rapid distillation at the
lower temperatures for alcohol-gasoline blends compared with gasoline
222,226,232 m, . . , . , r ,
alone. This despression of the front end of the
distillation curve can affect vehicle starting characteristics and
235
may allow for use of heavier components in the base gasoline.
The Reid Vapor Pressure of methanol-gasoline blends is higher than
either methanol-or gasoline-vapor pressures, and this may indicate
*? 9 fi 9^0
an increased tendency for vapor-lock problems,
Methanol-gasoline blends are known to be extremely sensitive
to the presence of small (—*0.1%) quantities of water. The water can
cause the separation of the blend resulting in the settling of a
water-methanol mixture to the bottom of the storage container
(222,225,226,232). fhe presence of higher alcohols can help
alleviate this phase separation, but quantities on the order of
several percent are required. While some vehicle-test programs have
233
not shown any problems with phase separation, others have
exhibited engine stall attributed to methanol separation in the
carburetor bowl. Large-scale use of methanol-gasoline blends
would require special water-free bulk distribution, vehicle-storage
and carburetor-bowl facilities to minimize moist air intrusion.
Attention has also been given to comparisons of engine
performance, fuel economy and emissions between vehicles fueled with
gasoline and those fueled with gasoline-methanol blends. If the
-------
231
vehicle carburetor is not adjusted, then the addition of ntethanol to
the gasoline causes a leaner overall stoichiomeCry, In this case
Federal-Test-Cycle evaluations with 10% methanol indicate a 507»
reduction in CO, a 10% reduction in NO , very little change in
x
unburned hydrocarbons, and a 107.. reduction in rniles-per-gallon fuel
231 2"M
economy. Other road tests also show the CO reduction, but do
234
not give consistent fuel economy results. Both slight improvements
9 *7 A
and slight losses in fuel economy have been reported. While some
road programs do not report driveability problems with methiinol
blends, other groups (with substantial driveability evaluation
experience) report significant driveability degradation with methanol
226,231
blends. Since the addition of methanol without carburetor
adjustment does lean the mixture, ye. would expect lean misfire
driveability problems on Late-model engines which are already
adjusted close to the lean limit. Addition of methanol and adjustment
of the carburetor to maintain stoichiometry would undoubtedly
compromise the above-mentioned CO emissions reduction. Federal-Test-
Procedure data for methanol-gasoline blends is shown in Figure 13.2
and Table 13,3,
Recent evidence indicates that vehicle fuel-tank and
distribution systems may experience severe corrosion problems with
226
methanol-gasoline blends.
In summary, methanol-gasoline blends can be used in conventional-
type engines provided carburetors are adjusted to maintain driveability,
Some reduction in CO emissions may result, but other emissions and
fuel economy will not be significantly altered. Careful attention must
be given to bulk fuel-distribution and storage systems and vehicle
fuel systems to avoid problems of phase separation and corrosion.
13,6 Reformed Fuels
The addition of small amounts of hydrogen to normal fuel systems
-------
232
2.0
E
o 5.0
I
nn
-
I*. . . .1
~^rt-
5=S
=H£
"=££
=i=:
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30
20
§
O
0
10
n
:i:-i:
jjj
2.0
1.0
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PPIpl*!*
UOJO!
c
c
f r
: -
:
"c
c
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IU
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O-
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m
FIGUKE 13.2 Emissions Data for Alcohol-Gasoline Blends, 1975 Federal
Test Procedures, 455 CID 1973 Engine with No Carburetion Adjustment.
Source: Reference 234
-------
233
TABLE 13.3
Test Data for 15% Methanol-Gasoline Blend
Exhaust Emissions, s/mi, Fed. Test Procedure
1967 Car Gasoline .
Gasoline + 15% methanol
1973 Car Gasoline
Gasoline + 15% methanol
"1975 Car" Gasoline
Gasoline + 15% methanol
1977 Federal Standards
Gasoline, mpg
Gasoline + 15% methanol5 mpg
% Change, rnpg
% Change, railes/Btu
HC
5.2
3.8
1.1
1.1
0.10
0.10
0.4
1967
(Rich)
14.3
14.4
+1
+8
CO
83
41
21
8
0,3
0.4
3.4
NO
X
6.4
8.1
2.6
1,7
2.6
2,3
1.5
Car
1973
(Lean)
11.2
10,6
-6
+1
Formaldehyde
0.13
0.20
0.075
0.10
0.002
0.004
"1975"
Catalyst Equipped
11.4
10.9
-4
+3
Notes
1)
2)
3)
Engines - 1967 289 CID V-8} air-gasoline equivalence ratio 0.9
1973 351 CID V-8, air-gasoline equivalence ratio 1.05
"1975"351 CID V-8, air-gasoline equivalence ratio 1.0
Carburetion was adjusted for gasoline-air mixtures and not changed
for blends.
The "1975" car was equipped with a catalytic converter.
REF 206
-------
(hydrogen-supplemented fuel) can extend the lean misfire limit for
spark- ignited, reciprocating engines to quite lean stoichiometry. Such
lean mixtures result in significant improvements in engine thermal
efficiencies and very low NO and CO emissions, but usually result
.X.
in higher unburned hydrocarbon emissions. One concept for obtaining
the required hydrogen involves reforming a portion of the gasoline to
hydrogen and carbon monoxide by means of an on-board partial oxidation
reforming unit. It is also possible to reform other fuels, such as
235
methanol, to obtain the hydrogen required. In this subsection
we review recent work with such hydrogen- supplemented fuel systems.
The effect of adding various amounts of hydrogen to single and
mu 1 1 icy 1 inder gasoline-fueled engines has been investigated at
220
General Motors Research Laboratories. Relatively small amounts of
hydrogen give dramatic reductions in the lean limit. In a single-
cylinder engine, a mixture of 5% H and 957, iso-octane (by mass)
extends the lean limit from an equivalence ratio ($) of 0.9 to about
0.7j while 107,, FL lowers the limit to = 0,5. With enough hydrogen
added to run at an equivalence ratio of 0,55, NO and CO emissions
x
are negligible, and unburned hydrocarbons are about the same as 100%
iso-octane at ji = 1. Under the same conditions, thermal efficiency
increases from 33% at i = 1 to 37% at i> = 0.55, while the power
output drops about 307,,
Vehicle tests with hydrogen-supplemented fuel were also carried
220
out. In tests with constant hydrogen mass flow, emissions were
measured using the Federal Test Procedure (hot start), and the results
are shown in Table 13.4 below. Also shown in Table 13.4 are emissions
obtained with a fuel-metering system which enabled the relative
amount of hydrogen in the fuel to be held constant. The results
indicate that lean operation with hydrogen-supplemented fuel does
dramatically reduce CO and NO emissions, but HC emissions are
x
relatively high.
-------
235
TABLE 13,4
Federal Test Procedure Emissions with
Hydrogen Supplemented Fuels,
Emissions (g/mi)
Constant Hydrogen Mass Flow Constant Hydrogen Fraction
NC> 1.3 0.39
Jt
CO 5.6 3.3
HC 2.6 3.1
REF 220
The initial hydrogen-supplemented fuel concept arose at Jet
rj -Q £"
Propulsion Laboratory (JPL) and a large program is underway there.'"
Single and multicylinder engine tests with added hydrogen confirm the
results noted above. The current reformer unit is a homogeneous,
partial-oxidation type, operating without water feed at 81% efficiency.
Development of catalytic-type reformers is also underway. The
catalytic reformers operate at much lower temperatures than the
homogeneous type and do not have the soot formation tendency. However,
they must be warm to function properly and require prevaporized fuel.
Limited vehicle tests with reformer-type products added to the
gasoline have been carried out at JPL. While the emissions results
were impressive on these tests, it was difficult to determine how
much improvement was due to the supplemented fuel and how much was
attributable to improved fuel vaporization and distribution due to the
use of a special atomizing carburetor. Such carburetors are known to
make leaner operation possible.
The reformed fuel concept is an attractive way to achieve the
lean operation required for low emissions and good fuel economy.
Reformer development and cycle testing are required to fully
demonstrate the system. After such demonstration, this concept should
-------
236
be carefully compared with other methods for achieving overall
lean operation.
13.7 ^hej^Jilter native Fuels
This subsection reviews several additional alternative fuels
which have been suggested for their low-emissions potential. These
fuels are all blends or emulsions containing a conventional fuel
and/or alcohol and water. In general, much less engine test data
is available for these compounds than for the previously discussed
fuels .
Water and gasoline or distillate combinations in which a
surfactant is added to emulisfy she water have been suggested as
engine fuels. In distillate combustion such emulsions result in a
micro-explosion of the water droplets before combustion because the
vapor pressure of the water is greater than the distillate vapor
pressure. This micro-explosion shoutd produce finer fuel sprays
237
and may reduce NO and soot emissions. Gasoline's higher
X.
volatility prevents the micro-explosion phenomenon from occuring in
gasoline-water emulsions and any reduction in HO would be due to
237 x
the cooling effect of the water. Also, if the carburetor is not
adjusted, metering the gasoline-water mixture instead of gasoline
results in leaner engine operation.
Limited emissions data are available from the California Air
Resources Board (ARE) cycle tests with "Vareb-10 Fuel", a fuel made
up of 57% Indolene, 38% Vareb emulsifier and 5% water by weight,
Cold-start test results are given in Table 13.5, taken from
Reference 238. CO and NO emissions were reduced, but cold-start
x
hydrocarbons increased. The hydrocarbon reactivity ratio also
increased with the water gasoline emulsion.
-------
TABLE 13.5
Effect of Vareb-10 on
Cold-Start Emission
Baseline
Test
Ho.
10
12
14
Avg.
1970 Chevrolet E 815472
HC
3.50
3.35
3.05
3.30
CO
39.08
36,00
24.48
33.19
Emissions
NOx
4.65
4.78
5.43
4.95
g/mt
CC-2
626
635
677
646
Aid.
0.091
0.076
0.067
0.078
React.
Ratio
0.471
0.448
0.474
0.464
Fuel Cons,
Weighted
1715
1748
1739
1734
g
Cal (1)
1649
1658
1710
1672
Vareb 10
Test
Ho.
11
13
ISA
Avg.
(1)
(2)
HC
3.53
3.79
3.48
3.60
Calculated
Multiplied
CO
9.83
9.84
9.11
9,59
from
by 0.
Emissions
NOx
2.14
2.26
2.08
2.16
_g/mi
CO?
651
657
695
668
emissions by carbon
836 to correct for
Aid.
0.063
0.105
0.092
0.087
balance.
14.4% HO.
React,
Ratio
0.582
0.569
0.583
0.578
Fuel Cons.
Weighed (2)
1684
1884
1827
1798
g
Cal (1)
1600
1616
1702
1639
REF 238
-------
238
Homogeneous blends of gasoline, isoprepyl or tertiary butyl
alcohol, and water have been patented by Freeh and Tazuma of Goodyear
239
Research Laboratories, The blends contain about 40% alcohol,
and water is added to the miscible range. It is proposed that these
large quantities of alcohol would be obtained by removing propene
and isobutene from, current refinery streams and converting them to
isopropyl alcohol or t-butyl alcohol. Only very limited vehicle-test
data is available for these blends, California cycle tests on a 1969
Dodge indicated reductions of 701-80% in CO, 30%-45% in H/C, and
25%-30% in NO . Fuel economy was not measured. Increases of about
3 RON per 107, alcohol are claimed for the blends. More vehicle-
test data and an analysis of the refining costs are necessary for a
full evaluation of the potential for these blends. In particular,
tests on late-model vehicles are not expected to show as large
an emissions reduction as noted above,
A water/methanol gasoline blend, in which a surfacant is
used to obtain a stable emulsion of the water/alcohol in the gasoline,
240
has been suggested as a emissions reducing fuel. Tests using a
7.5% methanol, TL surfacant, 0.5% water, 90% gasoline fueled 1973
vehicle (360 CID, A/F = 15.5:1, CR = 8,5:1) quite similar to previously
discussed methanol-gasoline blends. The leaning effect reduced CO
substantially but HC} NO and fuel economy were not significantly
^C
changed. The use of a surfactant to increase the water tolerance
of methanol-gasoline blends is noteworthy. If such a compound were
economically available in large quantities, it might help solve the
water sensitivity problem and make the use of gasoline-methanol
mixtures more attractive.
-------
REFERENCES
1. Furlong, L.E., E.L. Holt, and L.S. Burnstein, "Emission control
and fuel economy," a paper presented at the American Chemical
Society National Meeting in Los Angeles, April 1974.
2. "A Report on Automotive Fuel Economy/' EPA, October 1973.
3. LaPointe, Clayton, "Factors affecting vehicle fuel economy," SAE
Paper No. 73091, September 1973.
4. Fegraus, C.E., C.J. Domke, and J. Marzen, "Contribution of the
vehicle population to atmospheric pollution," SAE Paper No.
730520, May 1973.
5. Gumbleton, Bolton and Lang, "Optimizing engine parameters with
exhaust gas recirculation," SAE Paper No. 740104, February 1974.
6. Data obtained at meeting between NAS Technology Panel and General
Motors Corp., May 1974.
7. EPA data.
8. The Federal Register, Vol. XXXVII, No. 221, November 15, 1972.
9. Meeting at General Motors Corp. with NAS Technology Panel,
Augus t 1, 1974.
10. Petersen, Robert A. (American Motors Corp.) in letter to Emerson W.
Pugh (Executive Director, Committee on Motor Vehicle Emissions, HAS)
August 2, 1974.
11. Bowditch, Fred (General Motors Corp.) in letter to Robert F. Sawyer
(Consultant to the Committee on Motor Vehicle Emissions, NAS),
August 5; 1974.
12. W. Weber Master Catalog, Bologna, Italy.
13. Rochester Product Division, General Motors Corp., Catalog pp 10-11.
14. Private communications to CMVE consultants during visit to Wolfs-
burg, Germany, June 19, 1974.
15. "Modernizing the Fixed Venturi Carburetor," Automotive Engineering,
July 1974, p 46.
16. Larew, Walter, Carburetors and Carburetion, Chilton Publications,
p 136.
239
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240
17. Data presented to the Panel of Consultants on Engine Systems by
Holley Carburetor, May 14, 1974,
18. British Patent, 1223921, March 1971.
19. D.A. Trayser.
20. Dresser Industries, Inc., Environmental Technology Division letter
to Robert F. Sawyer (CMVE consultant), February 27, 1974; and
presentation by Ford Motor Co., Engine Research Office, Hay 16,
1974 (Figures 9 & 10).
21. Test of "Dresserator" Emission Control System, California Air
Resources Board, Project 235, May 1973.
22. Data presented to the Panel of Consultants on Engine Systems by
Ford Motor Co., May 16, 1974 (Figures 3 & 4),
23. Data presented to the Panel of Consultants on Engine Systems by
Ethyl Corporation, May 8, 1974.
24. John, James E.A. (CMVE consultant) Trip Report on visit to Shell
(Thornton) Research Ltd., Chester, England, June 145 1974.
25. Visit to British Leyland UK Ltd., Coventry, England by CMVE
consultants, June 18, 1974,
26, "Ultrasonic Fuel Systems,1' Popular Science, March 1973, p 89.
(Also, "Autotronics System," Hot Rod, January 1974.
27. Electrojector - Bendix Electronics, SAE Transactions, LXV, 1975,
p 758. (Also, Electronic Fuel Injection - "One Answer to Auto-
mobile Emissions Problem," Product Engineering, November 1973. p 73.
28. "Eine Electronische Gesteurte Kraftstoff Spritzung Fuer Ottomotoren,
MT2, XXVIII (1967) 11, p 475.
29. Communication to HAS consultants during visit to Volkswagenwerk AG,
June 19, 1974 and Robert Bosch GMBH, June 21, 1974.
30. Statement by Daimler-Benz, Stuttgart, Germany to CMVE consultants
during visit, June 20, 1974.
31. Statement by Saab-Scania Aktiebolag during Presentations of
Foreign Manufacturers, May 21-24, 1974, NAS, Washington, DC.
32. "Elecktronsche Benzin Einspritzung ntit Steuerung durch Lufttnenge
und Motordrehzahl," MTZ, XXXIV (1974), 4, p. 99.
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241
33. Statement by Volkeswagenwerk AG during Presentations of Foreign
Manufacturers, May 21-24, 1974, HAS, Washington, DC.
34. Visit to Bendix Corp EFI Division by CMVE consultants May 7,
1974 (Emissions Technology, p 21).
35. Statement by Volkeswagenwerk AG during Presentations of Foreign
Manufacturers, May 21-24, 1974, NAS, Washington, DC, pp 4.2, 4.9
and 8.2. (Also, see CMVE consultant E. Jost's summary of VW
presentation, p 2.)
36. Bosch Continuous Injection System, (15) Robert Bosch GMBH Publica-
tion, February 1, 1973.
37. "Bosch Develops Continuous Fuel Injection," Automotive Fngineering,
August 1973.
38. Statement by AB Volvo during Presentations of Foreign Manufacturers,
May 21-24, 1974, NAS, Washington, DC; also, p 32 of Volvo submis-
s ion.
39, Statement by Saab-Scania Aktiebolag during Presentations of Foreign
Manufactuers, May 21-24, 1974, NAS, Washington, DC.
40. "Closed-Loop Exhaust Emission Control System with EFI," SAE
Meeting May 14-18, 1973, Paper No. 730566.
41. Statement by Robert Bosch GMBH, Stuttgart, Germany during visit of
CMVE consultants, June 21, 1974.
42. Schweitzer, P.H., U.S. Patent 3,142,967, August 4, 1964; and
'ftdaptative Control for Prime Movers," ASME Paper, November 1967-
43. Visit to Ethyl Corp. by CMVE consultants, May 8, 1974.
44. Visit to Shell Research Ltd. by J.EUA. John, June 14, 1974,
45. Visit to Dresser Industries by CMVE consultants, April 1974.
46. Berriman, Lester (Dresser Industries) in letter to Robert F.
Sawyer (Consultant to Committee on Motor Vehicle Emissions),
May 10, 1974.
47. Austin, T. (Environmental Protection Agency) in letter to J.E.A.
John (Consultant to Committee on Motor Vehicle Emissions),
August 7, 1974.
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242
48. Visit to Ford Motor Co. by OWE consultants, May 1974.
49. CMVE Technology Panel meeting with Ford Motor Co., Dearborn, MI,
May 1974.
50. CMVE Technology Panel meeting with General Motors Corp., Techni-
cal Center, Warren, MI, Hay 1974.
51. Presentation by British Leyland UK Ltd, during Presentations of
Foreign Manufacturers, May 21-24, 1974, NAS, Washington, DC.
52. Presentation by Nissan Motor Co, , Ltd. during Presentations of
Foreign Manufacturers, May 21-24, 1974, MAS, Washington, DC.
53, Presentation by Toyota Motor Co. during Presentations of
Foreign Manufacturers, May 21-24, 1974, NAS, Washington, DC.
54, Visit to Gould, Inc., Cleveland, OH by J.E.A. John, CMVE consultant,
July 9, 1974.
55. Austin, T. (Environmental Protection Agency) in letter to J.E.A.
John (Consultant to Cottmittee on Motor Vehicle Emissions),
August 7, 1974.
56. Visit to Questor Corp., Toledo, OH by J.E.A. John, CMVE Consultant,
June 6, 1974.
57- Visit to General Motors, Warren, MI by CMVE Technology Panel,
May 1974.
58, Presentation of Foreign Manufacturers, May 21-24, 1974 3 NAS,
Washington, DC,
59. John, J.E.A,, Trip Report of visit to Robert Bosch GMBH,
Stuttgart, Germany, June 21, 1974.
60. Visit to Ford Motor Co., Dearborn, Ml, by CMVE Technology Panel,
May 1974,
61, "EPA; 1974 Model Year test Results," The Federal Register, Vol.
XXXIX, No. 40, Part 2, February 27, 1974.
62. Meeting with Foreign Manufacturers, May 21-24, 1974, NAS, Washington,
DC.
63. Wulfhorst, D., Trip Report o£ visit to General Motors Corp., Warren,
MI, June 21, 1974.
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243
64. Wulfhorst, D., Trip Report of visit Co Toyo Kogyo Co., Ltd.,
May 1974.
65. Ricardo, H.R., "Recent Research Work on Che Internal Combustion
Engine," SAE Journal, Vol. X, p. 305-336 (1922).
66, Bishop, I.I. and A. Siniko, Society of Automotive Engineers
Paper No. 680041 (1968).
67. Simko, A., M.A. Choma and L.L. Repco, Society of Automotive
Engineers Paper No. 720052 (1972).
68. Mitchell, E., J.M. Cobb and R.A, Frost, Society of Automotive
Engineers Paper No. 680042 (1968).
69. Mitchell, E. , M. Alperstein and J.M. Cobb, Society of Automotive
Engineers Paper No. 720051 (1972),
70. "1975-77 Emission Control Program Status Report," Submitted to
EPA by Ford Motor Co., November 26, 1973.
71. Presentation by Ford Motor Co. to CMVE Technology Panel, May 16,
1974.
72. Austin, T.C, and K.H. Bellman, Society of Automotive Engineers
Paper Ho. 730790 (1973).
73, Presentation by Texaco, Inc. to CMVE Technology Panel, March 28, 1974.
74, Alperstein, M., G.H. Schafer and F.J. Villforth III, SAE Paper
Ho. 740563 (1974).
75, Broderson, Neil 0., "Method of Operating Internal Combustion Engines,"
U.S. Patent No. 2,615,437 and No. 2,690,741, Rochester, New York.
76. Conta, L.D. and Pandeli, American Society of Mechanical Engineers
Paper No. 59-SA-25 (1959).
77, , American Society of Mechanical Engineers
Paper No. 60-WA-314 (I960).
78. Heintz, R.M., U.S. Patent No. 2,884,913, "Internal Combustion Engine."
79. Nilov, N.A., Automobilnaya Promyshlennost No. 8 (1958)»
80. Kerirnov, N,A= and R.I. Metehtiev, Automobilnoya Promyshlennost
No, 1, PP 8-11 (1967).
-------
244
81. Varshaoski, I.L,, B.F, Konev and V.B. Klatskin, Automobilnaya
Promyshlennost No, 4 (1970).
82. "An Evaluation of Three Honda Compound Vortex Controlled Combus-
tion (CVCC) Powered Vehicles," Report B-ll, Environmental Protec-
tion Agency, Test and Evaluation Branch, December 1972,
S3. "Automotive Spark Ignition Engine Emission Control Systems Panel
To Meet Requirements of the 1970 Clean Air Amendments," Com-
mittee on Motor Vehicle Emissions, NAS, May 1973.
84. "An Evaluation of a 300-CID Compound Vortex Controlled Combustion
(CVCC) Powered Chevrolet Impala," Report 74-13, DWP, Environmental
Protection Agency, Test and Evaluation Branch, October 1973.
85. General Motors Corp., Warren, MI Environmental Activities Staff,
Material submitted to the CMVE Technology Panel following presen-
tation on May 15, 1974.
86. Presentation by Honda Motor Co., Ltd, during Presentations of
Foreign Manufacturers, May 21-24, 1974, NAS, Washington, DC.
87. Nissan Motor Co., Ltd., Report submitted to members of the CMVE
Technology Panel, June 20, 1974.
88. Hewhall, H.K., and I.A. El-Messiri, Combustion and Flame, XIV,
pp 155-158 (1970).
89. , Society of Automotive Engineers
Paper No. 700491 (1970).
90. El-Messiri, I.A. and U.K. Newhall, Proceedings of the Intersociety
Energy Conversion Engineering Conference, p 63 (1971).
91. Ford Motor Co, Presentation to CMVE Technology Panel, January 24, 1974
92. Decker, G. and W. Brandstetter, MTZ; MotorEechnische Zeitschrjft,
Vol XXXIV, Ho. 10, pp 317-322 (1973).
93. John, J.E.A., Trip Report on visit to Volkswagenwerk AG, Wolfsburg,
Germany, June 19, 1974.
94. Report by Environmental Protection Agency, Ann Arbor, MI, January 23,
1974.
95. Springer, Karl J., "An Investigation of Diesel Powered Vehicle
Emissions," Interim Report by Southwest Research Institute to
the Environmental Protection Agency, Contract PH 22-68-23, June 1974.
-------
245
96. Campau, R.M., "Low emission concept vehicle," SAE Paper No. 710294,
1971.
97. Meguerian, G.H. and C.R. Lang, "NOX reduction catalysts for vehicle
emission control, " SAE Paper No. 710291, 1971.
98. Patterson, D.J. and N.A. Henein, Emissions from tombustion Engines
and Their Control (Ann Arbor Science Publishers, Inc., MI, 1972).
99. Hearings, Subcommittee on Air and Water Pollution, Committee on
Public Works, United States Senate, 93rd Congress, 1st Session,
May 14, 17, 18, and 21, 1973, Serial Ho. 93-H9.
100. General Motors Corp. presentation to CMVE consultants, February 14,
1974.
101. Perkins Engines presentation to CMVE consultants, June 1974.
102. Robert Bosch Corp. presentation to CMVE consultants, June 1974.
103. Monaghan, M.L., C.C.J. French and R.G. Freese, "A Study of the
Diesel as a Light Duty Power Plant," Ricardo and Co. Engineers
Report to the Environmental Protection Agency, Report No. EPA-
460/3-74-011, July 1974.
104. Dow Chemical U.S.A., seventeen reports on vehicle tests from
Dow particulate testing for the Environmental Protection Agency,
July 16, 1973-April 23, 1974.
105. Cental, James E., Otto J. Manary and Joseph C. Valenta, "Charac-
terization of Particulates and Other Non-Regulated Emissions from
Mobile Sources and the Effects of Exhaust Emissions Control Devices
on These Emissions," Dow Chemical U.S.A. Publication No. APTD-1567,
March 1973.
106. Caplan, John D., "Smog Chemistry Points the Way to Rational
Vehicle Emission Control, " SAE PT-12, XX, 1963-1966.
107. Altshuller, A.P, "An Evaluation of Techniques for the Determina-
tion of the Photochemical Reactivity of Organic Emissions,"
J. APCA, XVI, No. 5, 1966, p 257.
108. Henein, N.A. (CMVE Consultant) in letter to J. McFadden, EPA-
Ann Arbor, July 2, 1974.
109. Presentation by Peugeot, Inc. during Presentations of Foreign
Manufacturers, May 21-24, 1974, NAS, Washington, DC.
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246
110. Ford Motor Co. presentation to CMVE consultants, May 1974.
111. Pichford, J.H. , "The development of a small automotive diesel in
western Europe and its likely role in the USA," SAE Paper No. 215B.
112. Neild, G.C., "Delivering the mail with diesel--the Post Office
Department looks at diesel engines," SAE Paper No. 65071.
113. Pichford, J.H., et al., "What problems still restrain the small
automotive diesel engine?", presentation at FISITA Conference, 1964.
114. Daimler-Benz presentation to CMVE consultants, June 1974.
115. Perga, M.W and T.V. DePalma, "Diesel Engine Pollutants-Control,"
Hearings, Subcommittee on Air and Water Pollution, Committee on
Public Works, U.S. Senate, 93rd Congress, 1st Session, May 14,
17, 18, and 21, 1973, Serial No. 93-H9, p 956.
116. An Evaluation of Alternative Power Sources for Low Emission
Automobile^, Report of the Panel on Alternate Power Sources to
the Committee on Motor Vehicle Emissions, National Academy of
Sciences, April 1973.
117. Brogan, John J., "Alternative Powerplants," Advanced Automotive
Power Systems Development Division, U.S. Environmental Protection
Agency, IECEC, 1973.
118. "The automobile truck sector of transportation,"
Public Address, May 1974.
119. Eltinge, Lamont, "1970's Development of 21st Century Mobile-
Dispersed Power, A Challenge Requiring Nex
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247
124. Rogo, Casimir and Richard L. Trauth, 'Design of high heat release
Slinger combustor with rapid acceleration requirement," SAE
Automotive Engineering Congress, Detroit, MI, February 1974.
125. Zwick, E.B., and R.D. Bottos, "Development of Low Emission Combus-
tion System for the MERBC 10KW Turbo-Alternator,1T Zwick Co., May 1974,
126, Zwick Co., Santa Ana, CA, 4/11/74.
127. Solar, San Diego, CA, 4/10/74.
128. Jet Propulsion Laboratory, Altadena, CA, 4/9/74.
129. Ford Motor Co., Dearborn, MI, 2/13/74 -- gas turbines, Stirling
engines.
130, Chrysler Corp., Detroit, MI, 2/12/74 -- gas turbines.
131. Williams Research, Detroit, MI, 3/27/74 -- gas turbines.
132. Walzer, P., R. Buchheim, P. Rottenkolber, G. liagemann, "Pas-
senger Car Performance with the Experimental Gas Turbine VW—GT 70,"
ASME Publication 74-GT108.
133. Buchheim, Rolf, "Das Emissionsverhalten der Personenwagen-
Gasturbine VW-GT 70," Wolfsburg, MTZ Motortechnische Zeitschrift
35, 1974.
134. Walzer, Peter, Paul Rottenkolber, Gunter Hagemann, "Die Personnen-
wagen-Versuchsgasturbine VW-GT 70," Wolfsburg, Sonderdruck aus
MTZ Motortechnische Zeitschrift 34. Jahrgang, Franckh'sche
Verlagshandlung Stuttgart, Rummer 9/19/73.
135. Klarhoefer, C, "Optimization of the Idling and Acceleration
Characteristics of a Vehicular Gas Turbine by Analog Simulation,"
ASME Publication 74-GT-103.
136. Forschunasbericht, Nr. F3-73/18, Research Work at Volkswagen on
Gas Turbines.
137. Sheridan, David C., Gary E. Nordenson, and Charles A. Amann,
"Variable compressor geometry in the single-shaft automotive
Turbine Engine," SAE Automotive Engineering Congress, Detroit, MI,
February 1974.
138. Sanders, William A. and Hubert B. Probst, "Behavior of ceramics
at 1200° C In a simulated gas turbine enviornment," Ibid.
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248
139. Beck, Robert J. , "Evaluation of ceramics for small gas turbine
engines," Ibid.
140. Torti, M.L. , "Ceramics for gas turbines, present and future,"
Ibid.
141. Bratton, R.J., A.A. Holden and S.E. Mumford, "Testing ceramic staitor
vanes for industrial gas turbines," Ibid.
142. Noda, Furniyoshi, "Aluminum nitride and silicon nitride for high
temperature gas turbine engines," Ibid.
143. Wolkswagenwerk AG, Wolfsburg, W. Germany, 5/24/74 -- gas turbines.
144. Environmental Protection Agency, Ann Arbor, MI, 1/22-23/74.
145. Brobeck Associates, Berkeley, CA, 4/8/74 -- steam engine.
146. Steam Power Systems, San Diego, CA, 4/10/74 -- steam engine.
147. Jay Carter Enterprises, Burkburnett, TX, 4/12/74 — steam engine.
148. Scientific Energy Systems, Watertown, MA, 3/8/74 — steam engine.
149. Termo-Electron Corp., Waltham, MA, 3/8/74 -- organic Rankine cycle.
150. Teagan, W.P., and W. Clay. "3 KW Closed Rankine-Cycle Powerplant
with a Turbine Expander," Final Report, prepared for US Army
Mobility Research and Development Center, Electromechanical
Division, Ft. Belvoir, VA, Contract No. DAAK 02-72-C-0554,
Section E, Item #0002, Exhibit A, Item A005, Thermo-Electron
Corp., Waltham, MA, September 1973.
151. Hodgson, J.N., and F.N. Collamore, "Turbine Rankine cycle auto-
motive engine development," SAE Automotive Engineering Congress,
Detroit, MI, February 1974.
152. Hoagland, L.C. (Scientific Energy Systems Corp., Watertown, MA)
in letter to J.W. Bjerklie (CMVE consultant), March 19, 1974.
153. Hoagland, L.C,, R.L. Dernier, and J. Gerstmann, "Design features
and initial performance data on an automotive steam engine. Part I -
overall powerplant description and performance," SAE Automotive
Engineering Congress, Detroit, MI, February 1974.
154. Syniuta, W.D. and R.M. Palmer, "Design features and initial per-
formance data on an automotive steam engine. Part II - reciproca-
ting steam expander - design features and performance, Ibid.
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249
155. Patel, P., E.F. Doyle, R.J. Raymond, and R. Sakhuja5 "Automotive
organic Rankine-cycle powerplant - design and performance data,
Ibid.
156. Dutcher, Cornelius G,, Remarks before the Subcommittee on Space
Science and Applications of the Committee on Science and Astro-
nautics of the U.S. House of Representatives} February 6, 1974.
(Mr. Dutcher is with Steam Power Systems, San Diego, CA,)
157. Carter, Jay (Jay Carter Research and Development Engineers,
Burkburnett, TX) in letter to J.W. Bjerklie, May 19, 1974.
158. Minto, Wallace L. (President, Kinetics Corp., Sarasota, FL) ill
letter to J.W. Bjerklie, March 15, 1974.
159. Keller, Leonard J. (President, The Keller Corp., Dallas, TX) in
Letter to J.W. Bjerklie, March 22, 1974.
160. The Keller Corp. Memorandum, "External Combustion Engine Systems -
Recent developments and comments on state of the art," November 22,
1971.
161. Nichols, W.P- (President, Paxve, Inc., Costa Mesa, CA) in letter
to Emerson W. Pugh, Executive Director, CMVE), April 3, 1974.
162, Younger, Francis C., "Characteristics of the Brobeck steam bus
engine," SAE National West Coast Meeting, San Francisco, CA,
August 21, 1972.
163, Richardson, R.W., "Automotive Engines for the 1980's, Eaton's
Worldwide Analysis of Future Automotive Power Plants, Eaton Corp.,
Southfield, MI, July 1973.
164. __s Statement to the Subcommittee on Space Science
and Applications of the Committee on Science and Astronautics, U.S.
House of Representatives, June 13, 1974.
165. Philips Research Labs, Eindhoven,, Holland, 5/20/74 -- Stirling engines,
166. United Stirling, Malmo, Sweden, 5/21/74 -- Stirling engines.
167. MAH-MWM, Augsburg, W. Germany. 5/22/74 -•- Stirling engines.
168. Kinergetics, Tarzana, CA, 4/11/74 -- Stirling engine.
169. Postroa, Norman D. , Rob Van Giessel and Frits Reinink, "The Stirling
engine for passenger car application," SAE Combined Commercial Vehicle
Engineering & Operations and Powerplant Meetings, Chicago, IL, June 1973
-------
250
170, Carlqvist, S.G, and L.G.H. Qrtegren, "The potential impact of the
Stirling engine on environmental issues," prepared for presenta-
tion to The Institute of Road Transport Engineers, January 1974.
171. van Beukering, H.C.J, and H. Fokker, "Present state-of-the-art
of the Philips Stirling engine," SAE Combined Commercial Vehicle
Engineering & Operations and Powerplant Meetings, Chicago, IL,
June 1973,
172, Aim, C.B.S., S.G. Carlqvist, P.P. Kuhlmatm, K.H. Silverqvist,
and F.A. Zacharias, "Environmental characteristics of Stirling
engines and their present state of development in Germany and
Sweden," 10th International Congress on Combustion Engines, Paper
No. 18, 1973,
173, Kuhlmann, Peter, Das Kennfe_ld_ des Stirlingmotors, Augsburg, M.A.N.
Sonderdruck aus MTZ Hotortechnische Zeitsehrift, 34. Jahrg.,
Nr. 5/1173.
174, Asselinan, G.A.A. , J. Mulder, and R.J. Meijer, "A High-Performance
Radiator," Philips Research Labs., Eindhoven (The Netherlands),
1972.
175, "Hydorgen Safety of the Stirling Engine," Stanford Research Insti-
tute, Menlo Park, CA, January 4, 1974.
176. Stein, Robert A., "Progress Report on the Development of the
Valved Hot-Gas Engine," M. Thesis, ME Dept., MIT, January 1974.
177. MIT, Boston, MA, 3/8/74 — reciprocating Brayton engine.
178. Brobeck Associates, Berkeley, CA, Op. Git.
179. Post, Richard F. and Stephen F,, "Flywheels," Scientific American,
CCXX1K, No. 6, December 1973, p. 17."
180. Friedmanj Donald and Jerar Andon, "The Characterization of Battery-
Electric Vehicles for 1980-1990," Minicars, Inc., Golata, CA,
submitted by General Research Corp., Prime Contract No, EPA-
68-01-2103, January 1974.
181. Hamilton, William F., "Use of Electric Cars in the Los Angeles
Region 1980-2000," Preliminary draft RM1891 (EPA sponsored Elec-
tive Car Impact Study), General Research Co., Santa Barbara, CA,
April 1974.
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251
182. Foote, L.R., D.R. Hamburg, J.E. Hyland, C.W. Koop, W.H. Koch, and
L.E. Unnever, "Electric Vehicle Systems Study," Technical Report
No. SR-73-132, October 25, 1973, Ford Motor Co.,(Abbreviated ver-
sion: See Ref. 183.)
183. Unnever, Lewis, "Electric vehicle systems study," Paper No. 7414,
Third International Electric Vehicle Symposium, Washington, DC,
February 19-22, 1974, (UNIPEDE) (More detailed version: See Ref.
182.)
184. Hagey, Graham and William F. Hamilton, "Impact of electric cars
for the Los Angeles Intrastate Air Quality Control Region,"
Paper No. 7470, Ibid.
185. Bader, C.} and H.G. Plust, "Electrical propulsion systems for
Road Vehicles; State of the Art and Present Day Problems," Paper
No. 7478, Ibid. Also, Elektrische Antriebe fur Straszenfahrzeuge,
ETZ-A, 11,637 (1973).
186. "How Ford Evaluates Three Types of Electric Vehicles," Automotive
Engineering, LXXXII, No. 6, pp. 37-41, 75, June 1974.
187. Busi, James D., and Lawrence R. Turner, "Current Developments in
Electric Ground Propulsion Systems, R&D Worldwide," Journal of the
EJLectrochem. Soc. , CXXI, 183C, June 1974.
188. Healy, Timothy J., "The Electric Car: Will It Really Go?" I^EE
Spectrum, April 1974.
189. Linnenbom, V.J., "Battery Powered Buses in London," Office of
Naval Research, European Scientific Notes, ESN028-6, June 28, 1974.
190. Gross, Sidney, "Review of candidate batteries for electric vehicles,"
Battery Council International, preprint, Annual Meeting, London,
May 12-17, 1974.
191. Kamada, K. , I. Okazaki, and T. Takagaki, "Hew lead acid batteries
for electric vehicles and approach to their evaluation method,"
Paper No. 7429, Third International Electric Vehicle Symposium,
Washington, DC, February 19-22, 1974, (UNIPEDE).
192. "Research on Electrodes and Electrolyte for the Ford Sodium-
Sulfur Battery," Quarterly Report, Scientific Research Staff,
Ford Motor Co., KSF Contract NSF-C8Q5, January 1-March 1, 1974.
193. Sudworth, James L., "Some Aspects of Sodium Sulfur Battery Design,"
Preprint, 1974.
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252
194. Appleby, A.JC, J.J. Pompon, and M. Jacquier, "Zinc-air batteries
in vehicular applications," Paper No, 7430, Third International
Electric Vehicle Symposium, Washington, DC, February 19-22, 1974,
(UNIPEDE).
195. Nelson, P.A., A.A. Chilenskas, R.K. Stuenenberg," The Need for
Development of High Energy Batteries for Electric Automobiles,"
ANL-8075 (DRAFT), Argonne National Laboratory, January 1974.
196. Salihi, Jalal T., "Energy Requirements for Electric Cars and
Their Impact on Electric Power Generation and Distribution Systems,"
IEEE Transactions on Industry Applications, "Vol. IA-IX, Ho. 5,
September/October 1973.
197- Altendorf, J.P., A. Kaberlah and H. Saridakis, "A comparison
between a pick-up van with internal combustion engines and
an electric pick-up van," Paper Ho. 7445, Third International
Electric Vehicle Symposium, Washington, DC, February 19-22, 1974,
(UNIPEDE).
198. Woukj Victor and Charles L. Rosen, "Preliminary evaluation E.F.A.
test on PEM hybrid preliminary 'improvement package' information
for Phase II, F.C.C.I.P.," Paper No. 9336 Preliminary, April 4, 1974.
199. Mapham, Heville, "Conservation of petroleum resources by the use
of electric cars," preprint 740171, SAE Automotive Engineering
Congress, Detroit, MI, February 25-March 1, 1974.
200, Austin, A.L., "A Survey of Hydrogen's Potential as a Vehicular
Fuel," Lawrence Livermore Laboratory, Report Ho. UCRL-51228,
June 1972.
201, Pangborn, J.B., and J.C. Gillis, "Feasibility Study of Alternative
Fuels for Automotive Transportation," Institute of Gas Technology,
Interim Report on Contract Ho. 68-01,211, presented at AAPS
Coordination Meeting, May 1974.
202. Discussions with J. Pangborn (IGT), August 15, 1974.
203. Kant, F.H., "Feasibility Study of Alternative Automotive Fuels,"
Exxon Research and Engineering Co., Report No. EPA-460/3-74-009,
June 1974.
204. Jaffe, H., et al. , "Methanol from Coal for the Automotive Market,"
USAEC, February 1974.
205. Wentworth, T.O., as quoted in "Outlook Bright for Methyl-Fuel,"
Environmental Science and Technology, VII, 1973, p. 1002.
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253
206. Dutkiewicz, B., "Methanol Competitive with LNG on Long Haul,"
The Oil and Gas Journal. April 303 1973, p. 166.
207. "Coal Technology: Key to Clean Energy," Annual Report 1973-74,
Office of Coal Research, U.S. Department of the Interior.
208. Mills, G. and B. Ilarney, "Methanol - the 'New Fuel1 from Coal,"
Chemtech, January 1974, pp. 26-31.
209. Hammond, A., "A Timetable for Expanded Energy Availability."
Science, CLXXXIV, (1974), p. 367.
210. Hord, J., "Cryogenic H£ and National Energy Needs," presented at
Cryogenic Engineering Conference, August 1973.
211. Billings, R., "Hydrogen Storage for Automobiles Using Metal Hy-
drides and Cryogenics," presented at the Hydrogen Economy Miami
Energy (THEME) Conference, March 1974.
212. "Proceedings of the Hydrogen Economy Miami Energy (THEME)
Conference," Section 4, Metal Hydride Storage; Section 8, Hydrogen
Storage in Vehicles, March 1974.
213. King, R. , et al. , "The Hydrogen Engine: Combustion Knock and the
Related Flame Velocity," Transactions Engineering Institute of
Canada, II, No. 4, (1958), p. 143,
214. de Boer, P.} W. McLean, J. Fagelson, and H. Homan, "An Analytical
and Experimental Study of the Performance and Emissions of a
Hydrogen Fueled Reciprocating Engine," 9th IECEC, San Francisco,
August 1974.
215. Billings, R. and F. Cynch, "Performance and Nitric Oxide Control
Parameters of the Hydrogen Engine," Energy Research Publication
73002, Provo, Utah, April 1973.
216. Finegold, J., et al., "The UCLA Hydrogen Car: Design,
Construction and Performance," SAE Paper No. 730507 (1973).
217. , and M. Van Vorst, "Engine Performance with Gasoline
and Hydrogen: A Comparative Study," presented at the Hydrogen
Economy Miami Energy (THEME) Conference, March 1974.
218. Adt, R., et al., "The Hydrogen-Air Fueled Automobile," Proceed-
ings 8th IECEC, (1973), p. 194.
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254
219, Murray, R., R. Sehoeppel and C. Gray, "The Hydrogen Engine in
Perspective," Proceedings 7th IECEC> San Diego, September 1972.
220. Stebar, R, and F. Parks, "Emission Control with Lean Operation
Using Hydrogen - Supplemental Fuel," SAE Paper No. 740187,
February 1974.
221. "Alcohols and Hydrocarbons as Motor Fuels," SP-254, Society of
Automotive Engineers, Inc., New York, June 1964.
222. Bolt, J. , "A Survey of Alcohol as a Motor Fuel," Op Git., p. 1.
223. Adelman, H., D. Andrews and R, Devoto, "Exhaust Emissions from a
MethanoI-Fueled Automobile," SAE. Transactions , Paper No. 720693
(1972).
224. Ingamells, J,, "Discussion of SAE Papers 720692 and 720693,"
SAE Transactions, (1972), p. 2108.
225. Discussions with R, Hum, U.S. Bureau of Mines., Bartlesville
Energy Research, April 11, 1974.
226. IngamellSj J. and R. Lindqulsts "Methanol as a Motor Fuel," sub-
mitted by Chevron Research Co., (to be published in Science).
227. Starkinan, E., H. Newhall and R. Sutton, "Comparative Performance
of Alcohol and Hydrocarbon Fuels," Reference 221, p. 14.
228, Ebersole3 G. and F. Manning, "Engine Performance and Exhaust
Emissions: Methanol versus Isoctane," SAE Transactions, Paper
No. 720692 (1972),
229. Pefley, R., M. Saad, M. Sweeney, and J. Kilgroe, "Performance
and Emission Characteristics Using Blends of Methanol and Dis-
sociated Methanol as an Automotive Fuel," Pr_ogeed 1 ngs of 6th
IECEC, (1971), p. 36.
230, Reed., T, and R. Lerner, "Methanol: A Versatile Fuel for Immediate
Use," Science, CVXXXII, (1973), p. 1299.
231. Gallopoulos, N., "Alternate Fuels for Automobiles," General
Motors Research Laboratory; data submitted during panel of consul-
tants visit March 293 1974.
232, "Use of Alcohol in Motor Gasoline - A Review," American Petroleum
Institute, API Publication No, 4082, Washington, DC (1971).
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255
233, Reed,, T. , personal communication. May 1974.
234, Lerner, R.Me, et al. , "Improved Performance of Internal Combus-
tion Engines Using 5-20°i Methanol," (to be published).
235. NASA Lewis Research Center, Hydrogen Generator Program, informa-
tion provided during site visit, April 1974.
236. Breshears, R. , H. Cotrill and J. Rupe, "Partial Hydrogen Injec-
tion into Internal Combustion Engines, Effect on Emissions and
Fuel Economy," Jet Propulsion Laboratory Project Briefing,
February 1974.
237, Discussions with Dr. Fred Dryer, Princeton University, August 16,
1974.
238, "Evaluation of ?areb-10 Fuel Mixture," California Air Resources
Board, January 1974.
239, Freeh, K.J., and J.J. Tazuma, U.S. Patent Ho. 3822119. Also,
discussions with Dr. James Tazuma, Goodyear Research Laboratories,
August 16, 1974.
240, "Water/Alcohol Solutions in Internal Combustion Engine Fuel
Systems," Emission Free Fuels, Sparta, KJ3 December 1973.
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APPENDIX A
Organizations Contacted by Members of the
Panel of Consultants on Engine Systems
1.
2.
3.
4.
5.
6,
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
Ford Motor Co., Dearborn, MI
Chrysler Corp., Detroit, MI
Environmental Protection Agency,
Ann Arbor , MI
Chrysler Corp., Detroit, MI
Ford Motor Co., Ann Arbor, MI
General Motors Corp., Warren, MI
California Air Resources Board,
Los Angeles, CA
Dresser Industries, Santa Ana, CA
Philco-Ford, Newport Beach, CA
New York City Air Resources Board,
New York, NY
Curtiss -Wright Corp., Wood-Ridge, NJ
Texaco, Inc., Beacon, NY
Universal Oil Products,
Des Plaines, IL
Bendix, Detroit, MI
Ethyl Corp., Ferndale, MI
Holley Carburetor, Detroit, MI
Yanmar Diesel, Osaka, Japan
1/17/74
1/17/74
1/23/74
2/12/74
2/13/74
2/14/74
3/20/74
3/21/74
3/21/74
3/26/74
3/27/74
3/28/74
4/16/74
5/7-8/74
5/7-8/74
5/7-8/74
5/9/74
*John
John
John
John
John
John
John
John
John,
John
John,
John
John,
John,
John,
John,
Newhall
Wulfhorst
Jost
Jost
Jost
Jost
Wulfhorst
-«Last names of members of the Panel of Consultants on Engine Systems
256
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257
18. Toyo Kogyo Co., Ltd., 5/10/74
Hiroshima, Japan
19. General Motors Corp., Warren, MI 5/15/74
20. Ford Motor Co., Dearborn, MI 5/16/74
21. Chrysler Corp., Detroit, MI 6/4/74
22. TACOM, Detroit, MI 6/4/74
23. Questor Corp., Toledo, OH 6/6/74
24. Shell Research Ltd., Thornton, England 6/14/74
25. Ricardo & Co. Engineers, Ltd., 6/17/74
Shoreham-by-the-Sea, England
26. British Leyland Ltd., 6/18/74
Coventry, England
27. C.A.V., London, England 6/18/74
28. Toyo Kogyo Co., Ltd., 6/18/74
Hiroshima, Japan
29. Toyota Motor Co., Ltd., Aichi, Japan 6/18/74
30. Honda R&D Co., Ltd., Saitama, Japan 6/19/74
31, Perkins Engine Co., 6/19/74
Peterborough, England
32. Volkswagenwerk AG, 6/19//4
Wolfsburg, W. Germany
33. Daimler-Benz AG, Stuttgart, W. Germany 6/20/74
34. General Motors Technical Center, 6/20/74
Warren, MI
35. Japan Motor Vehicle Research 6/20/74
Laboratory, Osaka, Japan
36. Nissan Motor Co., Ltd., Tokyo & 6/20/74
Yokosuka, Japan
Wulfhorst
John, Newhall
John, Newhall
John
John
John
John
John, Henein, Jost
John, Jost
Henein
Newhall
Newhall
Newhall
Henein
John, Jost
John, Henein, Jost
Wulfhorst
Newhall
Newhall
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258
37. Daihatsu Kogyo Co., Ltd., Osaka, Japan 6/21/74 Newhall
38. Robert Bosch GMBH, Postfach, W. Germany 6/21/74 John, Henein, Jost
39. Audi, Ingolstadt, W. Germany 6/22/74 John, Jost
40. Ford Motor Co., Dearborn, Ml 7/9/74 Newhall
41. Gould, Inc., Cleveland, OH 7/9/74 John
42. General Motors Corp., Warren, MI 8/1/74 John
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259
APPENDIX B
Organizations Contacted by Members of the
Panel of Consultants on Alternatives
1, Environmental Protection Agency, 1/22-23/74, -Bjerklie, Tobias
Ann Arbor, MI 3/27/74, 7/2/74
2. ACAAPS Review Meeting, Washington, DC 2/11/74 Bjerklie
3. Chrysler Corp., Detroit, MI 2/12/74, 3/28/74 Bjerklie, McLean,
Wilson
4. Ford Motor Co., Dearborn, MI 2/13/74, 3/28/74 Bjerklie, McLean,
Wilson
5. General Motors Corp., Warren, MI 2/14/74, 3/26/74 Bjerklie, Tobias
6. Society of Automotive Engineers 2/27/74 Bjerklie
Meeting, Detroit, MI
7. Petro-Electric Motors, Ltd., March 1974 Bjerklie
New York, NY
8. Massachusetts Institute of Technology, 3/8/74, Bjerklie, McLean
Boston, MA May 1974
9. Scientific Energy Systems, 3/8/74 Bjerklie, McLean,
Watertovn, MA Wilson
10. Thermo-Electron Corp., Waltham, MA 3/8/74 Bjerklie, McLean,
Wilson
11. United Stirling (Sweden) in Boston, MA 3/15/74 Bjerklie
12. The Hydrogen Economy Miami Energy 3/18-19/74 McLean
(Theme) Conference, Miami Beach, FL
13. Institute of Gas Technology, 3/25/74, 8/15/74 McLean
Chicago, IL
14. Williams Research, Detroit, MI 3/27/74 BjerkLie, Wilson
*Last names of members of the Panel of Consultants on Alternatives
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260
15. Exxon Res, & Eng., Linden, NJ
16, Brobeck Associates, Berkeleys CA
17. Chevron Research Co., Richmond,CA
IB. University of California (Berkeley) CA
19. Jet Propulsion Lab., Altadena, CA
20. Solar, San Diego, CA
21. Steam Power Systems, San Diego, CA
22. Bartlesville Energy Research Center
(U.S. Bureau of Mines) Barltesville,OK
23. Kinergetics, Tarzana, CA
24, Philips Petroleum, Bartlesville, OK
25, Zwick Co., Santa Ana, CA
26. Jay Carter Enterprises, Burkburnett,TX
27. NASA Lewis Research Center,
Cleveland, OH
28. DAUG, Stuttgart, W. Germany
29. British Railway Tech. Ctr.,
Derby, England
30_ Philips Research Labs.3
Eindhoven, Ho Hand
31, United Stirling, Malmo, Sweden
32. MAN-MWM, Augsburg, W. Germany
33. Volkswagenwerk AG, Wolfsburg,
W. Germany
34. Princeton University, Princeton, NJ
35. Goodyear Research Labs», Akron, OH
4/3/74
4/8/74
4/8/74
4/8/74
4/9/74
4/10/74
4/10/74
4/11/74
4/11/74
4/11/74
4/11/74
4/12/74
4/12/74
5/15/74
5/16/74
5/20/74
5/21/74
5/22/74
5/24/74
8/16/74
8/16/74
McLean
Bjerklie
McLean
McLean
Bjerklie, McLean
Bjerklie, McLean
Bjerklie
McLean
Bjerklie
McLean
Bjerklie
Bjerklie
McLean
Bjerklie
Bjerklie
Bjerklie
Bjerklie
Bjerklie
Bjerklie
McLean
McLean
U.S. GOVERNMENT PRINTING OFFICE; 197S— 5B2-4I»:2J4
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