EPA/AA/TDG/93-04
Technical Report
Conversion of Methanol-Fueled 16-Valve,
4-Cylinder Engine To Operation On Gaseous
2H2/CO Fuel - Final Report
by
Ronald M. Schaefer
Fakhri J. Hamady
James C. Martin
March 1993
NOTICE
Technical Reports do not necessarily represent final EPA
decisions or positions. They are intended to present technical
analysis of issues using data which are currently available. The
purpose in the release of such reports is to facilitate the
exchange o£ technical information and to inform the public of
technical developments which may form the basis for a final EPA
decision, position or regulatory action.
U. S. Environmental Protection Agency
Office of Air and Radiation
Office of Mobile Sources
Regulatory Programs and Technology Division
Technology Development Group
2565 Plymouth Road
Ann Arbor, MI 48105
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
ANN ARBOR. MICHIGAN 48105
MAY -|
OFFICE OF
AIR AND RADIATION
MEMORANDUM
SUBJECT: Exemption From Peer and Administrative Review
FROM: Karl H. Hellman, Chief
Technology Development Group
TO: Charles L. Gray, Jr., Director?"
Regulatory Programs and Technology Division
The attached report entitled "Conversion of Methanol-Fueled
16-Valve, 4-Cylinder Engine To Operation On Gaseous 2H2/CO Fuel -
Final Report," (EPA/AA/TDG/93-04) describes the last phase of
testing on a project to convert a Nissan CA18DE engine previously
modified for operation on M100 neat methanol to operation on
dissociated methanol (2H2/CO) gaseous fuel. This engine was
operated on both M100 and simulated dissociated methanol (67
percent hydrogen and 33 percent carbon monoxide) fuels. This
report describes recent modifications made to the engine and fuel
delivery system and summarizes the results from recent testing on
both fuels.
Since this report is concerned only with the presentation of
data and its analysis, and does not involve matters of policy or
regulations, your concurrence is requested to waive administrative
review according to the policy outlined in your directive of April
22, 1982.
Concurrence:
Date: ?"~1 V^- 1L3
Charles L. Gray,/JfrC, Director, RPT
/ /
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Table of Contents
Pag*
Number
I. Summary 1
II. Introduction 2
III. Description of Test Engine and Fuel System Modifications. 3
IV. Exhaust Measurement Procedure . . 5
V. Discussion of Test Results 6
VI. Future Efforts 14
VII. Acknowledgments 14
VIII. References 14
APPENDIX A - Test Engine Specifications A-l
APPENDIX B - M100 Test Results B-l
APPENDIX C - 2H2/CO Test Results C-l
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I.
A 16-valve, 4-cylinder light-duty automotive engine has been
converted to operation on a mixture of hydrogen (Hj) and carbon
monoxide (CO) gaseous fuel in a 2:1 molar ratio of Hj and CO. This
engine has been used to investigate the difference in emission
levels and power output between two different fuels: M100 neat
methanol and simulated dissociated methanol gaseous fuel (2H2/CO).
Previously, several engine/fuel system modifications were made
in an attempt to increase power output when the gaseous fuel was
used [1]. Several intake port/fuel system configurations as well
as fuel injection nozzle designs were evaluated. These
modifications were evaluated to determine the effects of fuel
pressure, injection location, and fuel delivery methods on engine
performance. When using 2H2/CO fuel, the largest torque achieved
at 2,000 rpm, WOT operating conditions was 80 ft-lb. This
represents about 80 percent of the maximum torque levels obtained
with M100 fuel at the same WOT, 2,000 rpm operating conditions.
This torque level was considered satisfactory for gaseous fuel
operation. It was then necessary to monitor engine performance
(output torque, combustion efficiency, and emissions) at several
different operating conditions. This report summarizes engine
performance when operating on both M100 and 2H2/CO fuels at several
different operating conditions. The main goals of this final
testing were to demonstrate that there were certain operating
conditions where the engine produced more/similar torque, less CO
emissions, and had a better combustion efficiency when operating on
2H2/CO fuel.
When the 2H2/CO fuel was used, two different intake camshafts
.were used. The stock camshaft had the same cam profile for both
the air and fuel valves and was also used with M100 operation.
This camshaft was used when the torque value of 80 ft-lb was
achieved with the gaseous fuel. The modified camshaft had a very
short and fast valve lift for the fuel valve and the same air valve
event as the stock camshaft. The maximum torque achieved with this
camshaft during this testing was 43 ft-lb. Tests were conducted at
both 2,000 and 1,500 rpm.
When the stock intake camshaft was utilized with 2H2/CO fuel,
torque values were very similar to levels obtained with M100 fuel,
even higher at low loads (only varying by 20 percent at WOT) . At
high loads with the modified camshaft, torque values began to
decrease from M100 levels more rapidly, perhaps due to the very
short fuel valve event. However, there were several operating
conditions when using 2H2/CO fuel that resulted in higher torque
values than were achieved with M100 fuel.
The next goal was to operate the engine on 2H2/CO fuel and
achieve similar CO emission levels as when fueled with M100. With
the stock camshaft during medium-load operation, the engine
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produced somewhat similar levels of CO when operating on either
fuel. (2H2/CO fuel operation produced about 30 percent higher CO
emissions.) However, when the modified camshaft was used during
medium-load operation, both fuels produced almost equal amounts of
CO emissions.
The last goal of this program was to match combustion
efficiencies when using either fuel. During low to medium-load
operation, combustion efficiency values for each fuel were very
similar at 2,000 rpm. At higher loads, however, efficiency values
with the gaseous fuel begin to taper off from M100 levels.
This test program did meet the goals originally set for this
engine conversion program. First, the engine was successfully
converted to operation on simulated dissociated methanol fuel.
Also, after much engine and fuel system optimization work, the
engine did perform comparably to M100 operation when the 2Hj/CO fuel
was used. Similar torque values, CO emissions, and combustion
efficiencies were noted during low to medium-load operation for
both fuels.
II. Introduction
With recent advances in internal combustion engines and
emission control development, new technologies are being directed
toward improving combustion efficiency, multi-fuel capability, and
reduced emissions. Recent developments in engine technology have
enhanced stable burn and reduced emission levels. The use of
various alternative fuels is also being addressed to satisfy clean
air legislation for the 1990's.
One alternative fuel candidate is the concept of using exhaust
waste heat to provide the energy necessary for the dissociation of
methanol (CH3OH) to hydrogen and carbon monoxide. Methanol may be
catalytically decomposed to H2 and CO gases according to the
reaction:
CH3OH(0 2H2(W + COfc,
The decomposition of methanol to this gaseous fuel mixture has
been postulated as a more efficient method of using methanol as a
light-duty motor vehicle fuel. The major attraction of methanol
decomposition is that the resulting gases have a higher heating
value per pound than the original liquid methanol. A discussion of
the application of dissociated methanol as a light-duty automotive
fuel was presented in previous reports.[2,3]
In order to evaluate this concept, EPA modified a Nissan
CA18DE multi-valve engine to better utilize the combustion
characteristics of dissociated methanol fuel. This engine was a
stock model modified by Nissan Motor Corporation for use with
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liquid methanol. The engine was loaned to EPA by Nissan for use in
alternative fuels research. This report summarizes the most recent
EPA efforts in the investigation of dissociated methanol as an
automotive fuel for this engine.
The simulated dissociated methanol product gas used in this
work was a mixture of H2 and CO gases in the molar ratio 2H2/CO.
EPA did not possess a methanol dissociation system capable of
generating the necessary quantities of gaseous fuel at the time
work on this project was started; the engine was therefore tested
on a bottled gas mixture of 2H2/CO.
III. Description of Test Engine and Fuel system Modifications
Several modifications were made to this engine by EPA since
its delivery from Nissan; these modifications were detailed in
previous EPA technical reports.[1,2,4] This section will describe
the test engine and previous modifications made for operation on
2H2/CO fuel. This was the state of the test engine at the beginning
of the work described in this report.
The engine used for this project was a Nissan CA18DE engine
with an in-line, 4-cylinder, 1.8-liter capacity. The valve
arrangement is a 4-valve per cylinder configuration, consisting of
two intake and two exhaust valves per cylinder. The valves are
operated by dual overhead camshafts.
The test engine was initially modified by Nissan to better
utilize the qualities of M100 neat methanol over unleaded gasoline.
These modifications were discussed in detail in an earlier
report.[5] A summary of the test engine specifications when fueled
with M100 neat methanol is included in this report in Appendix A.
EPA then modified this engine for use with simulated
dissociated methanol fuel (67 volume percent Hj and 33 volume
percent CO) . The first was the installation, at Nissan's request,
of a thicker head gasket. This thicker gasket raised the clearance
between the valve face and the piston crown; this modification was
made to improve the durability of the engine. This thicker gasket
lowered the compression ratio from 11.0 to 10.5.
With M10O fuel, the engine utilized a 4-valve per cylinder
valvetrain configuration (two intake and two exhaust valves per
cylinder). When operating on the gaseous fuel, this arrangement
was modified to allow for admission of air to the cylinder through
one intake valve only; the second intake valve supplied the 2H2/CO
fuel. The exhaust side valve scheme was not altered (Figure 1) .
This configuration was used for all testing described in this
report with the 2HJ/CO fuel.
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Figure 1
Simulated Direct Injection Operation
Valve Scheme For 2H,/CO Fuel Use
This valve scheme allowed for the admission of gaseous fuel
through only one of the intake valves. An intake air control
assembly encloses the swirl control valves and is situated between
the intake manifold and the combustion chambers on the MIOO-fueled
engine. This assembly controls the air flow so that it is through
one intake runner and/or through both intake runners as necessary.
This is to control in-cylinder charge motion on the liquid-fueled
engine.
When the engine was converted by EPA to operation on 2H2/CO
fuel, the control valve slide and actuator were disassembled and
the swirl control valves removed. The runners through the valve
assembly that contained holes for fuel injectors were welded shut
approximately^ 1/2-inch upstream from the holes. These seals
prevented the admission of air to the ports through which the
gaseous fuel passes. The hole in the assembly left by the power
valve slide was sealed to prevent leakage of fuel and air between
runners.
With 2H2/CO fuel operation, two different intake camshafts were
utilized. The first was the stock M100 camshaft with similar air
and fuel valve events. The valve lift here was 0.335 inches with
a total valve event of 225°. The modified camshaft utilized
different valve events for both air and fuel. The air valve scheme
remained the same as the stock camshaft. The lobes on the fuel
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valves were altered to a total lift of 0.200 inches and a total
valve event of 100°. The development of this modified camshaft was
discussed in a previous report.[5]
Fuel injectors were not used to deliver the 2H2/CO fuel. The
rail and the individual injectors were removed and 3/8-inch inside
diameter stainless steel pipe fittings were used in their place.
The stainless steel fittings were threaded and the insides of the
aluminum injector holes were then threaded to adapt to the
fittings.
A fuel supply cylinder outside the test cell was used with 22
feet of 1/4-inch stainless steel tubing leading from the pressure
regulator on the cylinder to the solenoid valve inside the test
cell. The fuel leading from the solenoid valve to a flame arrester
was 3/8-inch in diameter and measured approximately 27 feet in
length. There were only slight bends and no turns in this fuel
line so that few pressure drops in the fuel delivery system would
occur.
Before the flame arrestor in the fuel line was a pressure
gauge that would measure fuel pressure to the intake manifold. Ten
feet downstream of the pressure gauge was another solenoid valve
followed by a 2-stage hydrogen flame arrestor. The mass flow
controller used previously to control 2H2/CO fuel was eliminated
from the fuel delivery system. This caused the engine to operate
at rich conditions when gaseous fuel was used.
The cylindrical plenum used previously to distribute fuel flow
to each cylinder was replaced with a 1/4-inch diameter fuel rail.
The fuel rail would distribute the incoming fuel to each of four
flexible fuel lines 3 inches in length leading to the fuel injector
ports. The total length from the intake valves to the flame
arrestor was approximately 11 inches.
The four fuel lines are connected to the same threaded
fittings which are screwed into the fuel injection posts in the
valve control assembly. The inside diameter of these fittings
(previously 1/4-inch) were replaced with different nozzle designs
to increase fuel pressure and enhance the fuel distribution. A
nozzle opening of 3 millimeters was used in this testing. The
gaseous fuel is supplied to the combustion chambers by the opening
of the fuel valves when the blockages in the intake air control
assembly were present. With these blockages, fuel flow to the
engine occurred through one intake valve and air through the other.
IV. Exhaust Measurement Procedure
Dilute emission samples were taken during this latest phase of
testing. Dilute emission samples were engine-out levels and taken
downstream of the exhaust manifold. These samples were taken as
engine exhaust passes from the exhaust pipe to a 2-1/2 inch
diameter flexible metal tube. This tube passes the exhaust
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overhead to a 6-inch rigid tube hung from ceiling supports. The
rigid tube delivers the exhaust to a Philco Ford 350 cfm constant
volume sampler (CVS). Total length of the flexible and rigid tube
sections is approximately 40 feet.
A gaseous sample line has been extended through the cell
ceiling and connects the mechanical CVS with an electronic display
panel in the cell control room. A fitting in the sample line at
the control room enables bag sampling at this point. Analysis of
bag samples is accomplished at a bank of analyzers located in
another test cell. Hydrocarbons (HC) emissions were measured with
a Beckman Model 400 flame ionization detector (FID). NOx level
determination was conducted on a Beckman model 951 chemiluminescent
NOx analyzer. Carbon oxides (CO, CO2) were measured by infrared
technique using a Horiba Model A1A23 infrared analyzer.
V. Discussion of Teat Results
The goal of this last phase of testing was to operate the
engine on M100 neat methanol and simulated dissociated methanol
(2H2/CO) fuels over a wide range of operating conditions to
determine if there were operating conditions on 2H2/CO fuel that
were comparable to M100 power output, CO emissions, and combustion
efficiency levels. First, testing was conducted at both 2,000 and
1,500 rpm when the engine load was varied from idle to wide-open-
throttle (WOT) with A/F ratio also being varied. The engine was
then converted to operation on 2H2/CO fuel while utilizing the stock
intake camshaft. Because each cylinder of fuel would operate the
engine for about 10-15 minutes, only selected operating conditions
were used here. Similarly, only a limited test sequence was
followed when the stock intake camshaft was replaced with the
modified version for 2H2/CO fuel use. The spark timing for testing
.on M100 fuel was kept at 20°BTDC; similarly, with 2H2/CO fuel, the
spark timing was kept at 5°BTDC. Fuel pressure with M100 was 45
psig, and 75 psig with 2H2/CO. Only selected operating points were
selected where the engine ran very smooth when 2H2/CO fuel was used.
Figure 2 below presents brake specific torque results while
using either fuel at 2,000 rpm. The horizontal axis represents the
percentage of throttle opening (100 percent throttle opening
represents WOT). Also, this data was obtained under rich
conditions- of Lambda equal to 0.7. From this plot, brake specific
torque during low load operation (25 percent throttle opening) is
higher with the 2Hj/CO fuel than with M100. During medium load
operation (40-65 percent throttle opening), only a slight torque
deviation from M100 levels results when operating on the gaseous
fuel with the stock intake camshaft. Using the modified camshaft
results in a larger drop in brake specific torque at higher engine
loads. At WOT, there is about a 20 percent difference in power
output between the two fuels using the stock camshaft. Operation
with the modified camshaft resulted in leaner operating conditions
because of the reduced fuel valve lift and duration.
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Figure 2
Brake Specific Torque Values
Lambda = 0.7, 2000 rpm Operating Conditions
Torque (ft-lbs)
120
100
80
60
4O
20
Camshaft/Fuel
— Stock/M100
-°- Stock/H2CO
•»• Mod./H2CO
25 50 75
Throttle Opening (%)
100
These trends in brake specific torque were also noted during
similar testing at 1,500 rpm. Again, these results were obtained
at rich conditions of a Lambda equal to 0.7. Also, at lighter
loads below 30 percent throttle opening, brake specific torque
levels with the gaseous fuel and the stock intake camshaft were
larger than corresponding M100 levels. At these conditions, the
modified camshaft testing also yielded similar torque levels as
M100 fuel. During medium load testing, torque values associated
with 2H2/CO fuel use begin to fall below M100 levels. With the
stock camshaft, torque values are only slightly lower than M100
levels, but using the modified camshaft has an even more
detrimental affect on torque. Above 75 percent throttle opening,
torque value* associated with 2H2/CO fuel fall well below M100 fuel
levels. At WOT, the stock camshaft testing yielded a torque
approximately 53 percent below M100 levels. This reduction in
torque may be attributable to not adjusting the spark timing for
changes in air/fuel richness at higher load conditions.
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Figure 3
Brake Specific Torque Values
Lambda = 0.7*, 1500 rpm Operating Conditions
100
80
60
40
20
Torque (ft-lbs)
Camshaft/Fual
-~Stock/M100
•°-Stock/H2CO
-*- Mod./H2CO
0 25 50 75
Throttle Opening (%)
* Operated slightly leaner with modified camshaft
100
The second goal of this test program was to determine if there
were operating conditions with 2Hj/CO fuel that produced less CO
emissions than with M100. As was the case with torque output, CO
emission levels were indeed comparable between 2HJ/CO fuel operation
and M100 at some operating conditions. Figure 4 below presents CO
emission levels in grams/BHP-hr over a wide range of load operation
for each fu«l^at 2,000 rpm.
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Figure 4
Brake Specific Carbon Monoxide Emissions
Lambda = 0.7, 2000 rpm Operating Conditions
500
400
300
200
100
BSCO (g/Bhp-hr)
Camshaft/Fuel
— Stock/Ml 00
•*• Stock/H2CO
•*• Mod./H2CO
25 50 75
Throttle Opening (%)
100
At light loads (25 percent throttle opening), both fuels
produced a large amount of CO emissions. However, when using the
gaseous fuel, CO emissions at light loads were about 29 percent
ftigher than M100 levels. During medium load operation, CO levels
with 2H,/CO fuel dropped below the light-load M100 levels. However,
with the stock intake camshaft, the difference in CO levels between
M100 and 2H,/CO fuels at each operating point remained similar to
the difference during light-load operation (about 30 percent).
However, when the modified intake camshaft was used, CO levels
between the two fuels were approximately equal at a throttle
opening of 66 percent.
Figure £ presents CO emission levels from testing at a 1,500
rpm engine speed. During this testing, operating on 2Hj/CO fuel
resulted in higher CO emission levels for every operating condition
investigated. CO levels with M100 fuel at 1,500 rpm were also much
lower than when operating at 2,000 rpm. With the stock intake
camshaft and 2H2/CO fuel, CO emission levels remain approximately
twice as large as corresponding M100 levels over the entire engine
load range investigated. Below 75 percent throttle opening, the
use of the modified camshaft resulted in higher CO emissions than
the stock camshaft.
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Figure 5
Brake Specific Carbon Monoxide Emissions
Lambda = 0.7*, 1500 rpm Operating Conditions
600
500
400
300
200
100
BSCO (g/Bhp-hr)
Camshaft/Fuel
~-Stock/M100
-°- Stock/H2CO
-*• Mod./H2CO
0 25 50 75
Throttle Opening (%)
Operated slightly leaner with modified camshaft
100
Obtaining lower CO levels with 2H2/CO fuel than with M100 seems
to be very difficult. Although torque levels were greater at some
operating points with 2H2/CO fuel, it was not possible to obtain
lower CO emissions with this fuel when compared to M100 levels.
This could be partly attributable to unburned fuel and incomplete
combustion, both contributing to CO formation when 2H2/CO fuel is
used, especially at rich conditions. With N100, only incomplete
combustion contributes to this phenomenon. Also, during testing
with the gaseous fuel, it was not possible to fully warm the engine
prior to emissions testing because of the limited amount of fuel
present irv the gas bottle. The engine oil temperature during
emissions tasting with M100 fuel was about 180-200°F; the
corresponding temperature with 2H2/CO fuel was 90-120°F. Therefore,
the combustion chamber was much colder, resulting in greater
amounts of unburned fuel and incomplete combustion, both
contributing to higher CO emissions.
The last goal in this test program was to operate the engine
on 2H2/CO fuel at a greater combustion efficiency than when operated
on M100. Figure 6 below presents combustion efficiency values
over the same engine load range at 2,000 rpm and Lambda = 0.7
conditions.
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Figure 6
Brake Thermal Efficiency Values
Lambda = 0.7, 2000 rpm Operating Conditions
Efficiency (%)
30
25
20
15
10
Camshaft/Fuel
•~Stock/M100
-°- Stock/H2CO
•*• Mod./H2CO
25 50 75
Throttle Opening (%)
100
Combustion efficiency was calculated based on the brake
horsepower output, fuel consumption, and heat of combustion of the
fuel used by the following formula:[6]
= [BHP x
Where:
H = Brake thermal efficiency
BHP = Brake horsepower
K,, = Value of 1 hp expressed in (force x length/time)
units
J =•• Joule's law constant
Mf * Macs of fuel supplied per unit time
Qe » Heat of combustion of a unit mass of fuel.
Low load operation below 30 percent throttle opening using the
2Hj/CO fuel with the stock intake camshaft resulted in higher brake
thermal efficiency values than when operating on M100. At greater
loads with the stock intake camshaft, brake efficiency values begin
to diverge below corresponding M100 levels, resulting in about a 10
percent thermal efficiency difference at WOT operating conditions.
Again, this plot is only for rich operating conditions of Lambda -
0.7.
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Testing with the modified intake camshaft also provided
operating points where the engine was more efficient operating on
gaseous fuel than with M100. At about half throttle, the brake
thermal efficiency when operating on 2H2/CO fuel was slightly
greater than the M100 efficiency curve. However, as the engine
load was increased, efficiency values with the modified intake
camshaft dropped substantially. However, there again were
operating conditions at Lambda = 0.7, 2,000 rpm where the engine
was more efficient operating on 2H2/CO fuel.
Figure 7 presents similar traces of brake thermal efficiency
for each fuel, however, when operating at 1,500 rpm. Again, below
a throttle opening of about 40 percent (low load), brake thermal
efficiencies were greater when operating on 2H2/CO fuel rather than
M100. This was the case for both the stock and modified camshaft.
During middle to full load operation, brake efficiency values
dropped off considerably from corresponding M100 levels. This
efficiency drop may again be attributed to not adjusting the spark
timing when the engine was operated at leaner conditions here. At
WOT, a thermal efficiency difference of 15 percent results between
operation on the two fuels. However, at lower loads, the goal of
higher brake thermal efficiencies on dissociated methanol fuel
operation was realized.
Figure 7
Brake Thermal Efficiency Values
Lambda = 0.7*, 1500 rpm Operating Conditions
Efficiency (%)
Camstaft/Futf
~Stock/M100
-°- Stock/H2CO
* Mod./H2CO
25 50 75
Throttle Opening (%)
* Operated slightly leaner with modified camshaft
100
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Again, all the previous figures' results were obtained at rich
operating conditions (Lambda = 0.7). This was the case because the
fuel controller used previously during 2H2/CO fuel operation was
eliminated from the fuel delivery system. An air/fuel ratio was
used to monitor richness with both fuels. The stock intake
camshaft always allowed the engine to operate at a Lambda value of
0.7 at a fuel delivery pressure of 75 psig. However, when the
modified intake camshaft was used, engine operation became much
leaner, varying anywhere between a Lambda value of 0.8 to 1.1,
depending on throttle position. The air/fuel richness when
operating on M100 was controlled by an external controller provided
to us by Nissan. The air/fuel value would be changed by turning
the dial and monitoring the Lambda value on the air/fuel ratio
meter.
Appendix B of this report contains all the power output,
efficiency, and emissions data from testing on M100 fuel at both
2,000 and 1,500 rpm conditions. The test sequence started with
selecting the WOT condition, and emission bag samples and torque
values were taken at three different fuel richness points: rich
(Lambda = 0.7), stoichiometric (Lambda = 1.0), and lean (Lambda =
1.4). Four throttle openings were evaluated; 100 percent (WOT), 75
percent, 50 percent, and 25 percent throttle openings. All
emissions values are presented in brake specific form (grams per
brake horsepower-hour) and are engine-out levels; there was no
catalyst present in the exhaust system.
When operating on M100, the engine produced much higher
emissions levels of hydrocarbons and CO at rich conditions (Lambda
=0.7). At rich conditions, these levels were approximately ten
times higher than when operating at stoichiometric. The largest
brake specific horsepower was obtained at WOT and rich conditions
and was measured at 39.2 at 2,000 rpm. The greatest brake thermal
efficiency on M100 fuel was 36.3 percent at WOT, lean operation
(Lambda = 1.3), and 2,000 rpm. Similarly, the highest efficiency
at 1,500 rpm was also noted at this same operating point.
Appendix C presents similar data when operating on 2H2/CO fuel
with the stock and modified intake camshafts. Again, the limited
amount of fuel in the gas cylinders allowed for data collection at
only a few test points (indicated by percent throttle opening).
The overall goals of operating on 2H2/CO fuel at higher efficiencies
and torque were realized at low load operation. This, however, was
not the case at higher loads. Operating on 2H2/CO fuel while
producing lower levels of CO emissions were more difficult to
attain. Because of the CO content in the fuel itself, operating on
dissociated methanol always produced more CO emissions than M100 at
the same operating points. However, through the recent engine and
fuel system modifications described previously, CO levels produced
during 2H2/CO fuel operation here were much lower than those
produced anytime previously.[1]
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In the prior interim report,[l] the combustion process was
monitored using an in-cylinder pressure transducer. Previously,
engine operation on dissociated methanol fuel was smoother and
offered less fluctuation in maximum cylinder pressure values (a
more stable combustion process). It was again attempted to monitor
this data, however, error and resonance in the pressure transducer
did not allow for accurate data presentation.
VI. Future Efforts
A 100 percent efficient methanol dissociator is currently not
available. The initial goal of this engine conversion project was
to convert an MIOO-fueled engine to operation on simulated
dissociated methanol fuel. The engine is currently able to operate
on 2H2/CO fuel at higher power output and greater thermal efficiency
than when fueled with M100 at certain operating conditions. EPA
does not plan any additional engine testing until an acceptable
methanol dissociator becomes available.
VII. Acknowledgments
The CA18DE engine described in this report was modified for
use with M100 neat methanol and loaned to EPA by the Nissan Motor
Corporation as support for an effort to investigate the potential
of neat methanol as an alternative motor vehicle fuel. The authors
appreciate the efforts of Jennifer Criss and Mae Gillespie of the
Technology Development Group for word processing support.
VIII. References
1. "Conversion Of Methanol-Fueled 16-valve, 4-Cylinder
Engine To Operation On Gaseous 2H2/CO Fuel-Interim Report IV,"
Schaefer, R. M., et al., EPA/AA/TDG/92-06, September 1992.
2. "Conversion Of Methanol-Fueled 16-Valve, 4-Cylinder
Engine To Operation On Gaseous 2H2/CO Fuel-Interim Report II,"
Piotrowski, G. K. and J. Martin, EPA/AA/CTAB/89-02, March 1989.
3. "Resistively Heated Methanol Dissociator For Engine Cold
Start Ass 1st-Interim Report," Piotrowski, G. K., EPA/AA/CTAB/88-02,
March 1988.- -,
4. "Conversion of Methanol-Fueled 16-Valve, 4-Cylinder
Engine To Operation On Gaseous 2H2/CO Fuel-Interim Report III,"
Schaefer, R. M. et al., EPA/AA/CTAB/91-01, April 1991.
5. "Conversion of Methanol-Fueled 16-Valve, 4-Cylinder
Engine to Operation On Gaseous 2H2/CO Fuel-Interim Report,"
Piotrowski, G. K., EPA/AA/CTAB/88-06, June 1988.
6. The Internal ^-Combust ion Engine in Theory and Practice.
Volume 1. Taylor, C. P., The M.I.T. Press, 1985.
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A-l
APPENDIX A
TEST ENGINE SPECIFICATIONS, M100 FUEL OPERATION
CONDITION AS LOAN BY NISSAN TO EPA
Manufacturer
Basic engine designator
Displacement
Cylinder arrangement
Valvetrain
Combustion chamber
Bore X Stroke
Compression ratio
Compression pressure
Fuel control system
EGR
Valve clearance
Idle speed
Engine oil
Fuel
Air/fuel control
Spark advance control
Nissan Motor Co., LTD
CA18DE
1809 cc
4-cylinder, in-line
Dual-overhead camshaft
Pentroof design
83 mm x 83.6 mm
10.5
16.5 kg/square cm (350 rpm, 80°C)
Electronically controlled
fuel injection
EGR not used
0 mm (automatically adjusting)
750 rpm
Special formulation supplied by
Nissan for methanol
engine operation
Ml00 neat methanol
Excess air ratio may be varied from
0.5 to 2.0 by means of
an external control
Ignition timing can be varied
from 0°BTDC to 54°BTDC by means
of an external control
-------
B-l
APPENDIX B
MIPOTESTRESULTS
2,000 RPN Conditions
Lambda
Torque
(ft-lb)
g/BHP-hr
BSHC
BSCO
BSNOX
BSCO
Effic.
(%)
BHP
Wide-Open Throttle:
0.7
1.0
1.3
103
94
78
10.37
0.45
0.64
229.7
37.5
3.9
3.9
9.1
4.6
399
448
466
28.2
35.2
36.3
39.2
35.8
29.7
75 Percent Throttle opening:
0.7
1.1
1.4
62
58
40
15.64
1.42
1.62
244.6
22.0
3.5
0.9
6.6
1.2
404
557
589
23.2
31.9
27.9
23.6
22.1
15.2
50 Percent Throttle Opening:
0.7
1.1
1.4
44
36
22
2.66
0.41
3.63
203.3
6.3
6.9
0.2
3.6
1.0
404
599
776
22.0
26.7
21.0
16.8
13.7
8.4
25 Percent Throttle Opening:
0.7
1.0
1.4
6
6
0
8.64
1.32
NA
346.2
22.6
NA
0.8
1.2
NA
1595
1762
NA
6.2
8.4
0.0
2.3
2.3
0.0
NA = Not available
-------
B-2
APPENDIX B (cont'd)
Ml00 TEST RESULTS
1,500 RPM conditions
Lambda
Torque
(ftlb)
g/BHP-hr
BSHC
BSCO
BSNOX
Wide-Open Throttle:
0.7
0.1
1.4
93
85
69
25.35
2.88
1.18
133.8
16.9
2.7
5.5
10.1
3.2
BSCOj
Effic.
(%)
428
457
461
24.7
30.7
35.0
BHP
26.6
24.3
19.7
75 Percent Throttle Opening:
0.7
1.0
1.4
62
58
40
26.44
1.43
1.40
140.3
16.6
2.4
1.9
7.2
1.9
428
510
561
22.1
28.3
27.3
17.7
16.6
; 11.4
50 Percent Throttle Opening: :
0.7
1.0
1.4
45
37
25
3.87
1.08
1.87
147.9
7.2
1.8
0.3
4.2
0.9
393
576
536
21.8
24.4
23.0
12.9
10.6
7.1
25 Percent Throttle Opening:
0.7
1.0
1.4
10
11
2
5.01
0.94
16.60
168.1
14.1
15.0
0.4
1.2
1.9
851
1024
4177
9.8
14.3
3.9
2.9.
3 . i ;•
0.-6
i
-------
C-l
APPENDIX C
2H,/CO TEST RESULTS
Stock Intake Comshaf t Testing
%WOT
Torque
(ftlb)
g/BHP-hr
BSHC
BSCO
BSNOX
BSC02
Effio
(%)
BHP
2,000 rpm
25
50
53
56
12
36
42
42
0.22
0.07
0.02
0.04
445.0
288.0
284.9
283.3
0.2
0.8
0.2
0.4
524
415
394
443
11.0
16.6
19.6
17.0
4.6
13.7
16.0
16.0
1,500 rpm
33
.. .-• 59,
100
28
48
44
0.01
0.04
0.03
308.2
269.5
285.1
0.1
0.7
0.2
336
394
358
16.8
16.4
8.9
8.0
13.7
12.6
Modified Intake Camshaft Testing
Lambda
%WOT
Torque
(ftlb)
g/BHP-hr
BSHC
BSCO
BSNOX
BSCO2
Effic
(%)
BHP
„ 2,000 rpm ....... : ...
l.l
0.9
46
66
1,500 rp»
1.1
0.8
32?
74
29
36
0.03
0.02
317.9
241.3
17.1
13.1
676
624
21.4
15.3
10.9
13.7
18
43
0.06
0.05
485.2
253.1
4.6
21.7
688
618
16.6
12.8
5.1
12.3
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