74-31 AEB
Exhaust Emissions Tests of the Carter Steam Car
June 1974
Technology Assessment and Evaluation Branch
Office of Mobile Source Air Pollution Control
Emission Control Technology Division
Environmental Protection Agency
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Background
Jay Carter Enterprises of Burkburnett, Texas, has designed
and built a steam Rankine cycle power system. This system
was installed in a Volkswagen station wagon to demonstrate
their approach to the Rankine cycle system. Carter Enter-
prises developed their system over the past six years with
no financial assistance from the Government or any company.
Since their own emission tests indicated that the vehicle
was close to meeting the original (1976) statutory emission
levels, Carter Enterprises contacted the Alternative Auto-
motive Power Systems Division (AAPSD) of EPA and arrangements
were made for exhaust emissions tests at the Motor Vehicle
Emissions Laboratory in Ann Arbor, Michigan. The tests of
the steam car reported herein were conducted during separate
one-week periods in March and May of 1974. The emissions
tests were conducted by the Technology Assessment and
Evaluation Branch of the Emission Control Technology Division
at the request of AAPSD as part of a continuing effort to
stay abreast of alternative power systems development and
assess the emission control potential of such systems.
Carter Enterprises provided personnel to operate the car
and interpret engine parameter data.
Vehicle Description
The Carter Rankine cycle system is installed in a Volkswagen
"Squareback" station wagon. The standard VW four-speed trans-
axle is used, with the steam system occupying the normal engine
compartment except for a small ram-air condenser located at
the front of the vehicle. An additional small forced-air
condenser is at the rear of the vehicle. The expander is a
four-cylinder radial, single acting uniflow engine^without
crossheads and is designed to operate on 2000 psi steam
pressure at 1000"F with a maximum driveshaft speed of 5000 rpm.
The boiler is a variable pressure monotube type fired by a
modulating burner utilizing a modified spinning cup fuel
atomizer. Fuel used was a blend of 50% (by volume) Indolene
gasoline and 50% kerosene. The complete steam system in its
present prototype configuration weighs approximately 120 pounds
more than the original internal combustion engine. The dry
weight of the car is 2470 pounds. Vehicle test instrumentation
was neatly packaged in the vehicle dashboard. Externally the
vehicle closely resembled the original vehicle.
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-2-
A standard 1974 Volkswagen type 111/113 "Super Beetle" was
also tested to compare steady state fuel economy.
All testing was done at an inertia weight of 2750 pounds to
simulate the weight of the vehicle and two passengers.
Test Procedure
The car was tested according to conventional Federal procedure,
except where the nature of the engine or unique tests required
special procedures and deviations to be employed. The Federal
procedures include operation of a vehicle on a chassis dyna-
mometer using simulated road loads, with exhaust emissions
analysis by the Constant Volume Sampling (CVS) method.
The special procedures used in the tests of the Carter steam
car included:
1) use of an electric chassis dynamometer instead of the
conventional Clayton water brake dynamometer.
2) delivery of engine cooling air as a function of vehicle
speed rather than by the fixed-speed fan specified in the
conventional procedures.
3) removal of one air filter from the dilution box to reduce
backpressure in the car's exhaust system.
4) use of a special system for exhaust hydrocarbon analysis.
j , •
5) a deviation from the startup and warmup phases of the
driving schedule. . .
These special procedures and the reasons for using them, are
described in more detail below. Figure 1 is a schematic
drawing of the test setup.
Operating Modes: The car was tested by the 1975 Federal Tes^t
Procedure (FTP) for exhaust emissions and urban fuel economy.
This procedure uses the LA-4 driving schedule. For highway fuel
economy the Federal Highway Fuel Economy test was conducted.
Finally, for steady state data and engine/emissions mapping,
the car was tested on the chassis dynamometer at idle and at
various constant speeds up to 60 mph.
Dynamometer: Instead of the double-roll Clayton water brake
chassis dynamometer used in most EPA testing, an electric
chassis dynamometer with a large (48" dia.) roll was employed.
The reason for using the electric dynamometer was that the
Carter car required ram-air cooling for the steam condenser
and the electric chassis dynamometer system used included a
blower which delivered air flow over the car as a function of
-------
-3-
roll speed. In the normal Federal Test Procedure a fixed
speed fan delivers air to cool the engine, but in the case
of the Carter car the amount of cooling air would be too
great at idle and low speeds, and too little at high speeds
for the condenser requirements.
In addition, for steady state tests, the engine power could be
determined by motoring the vehicle with the electric dynamometer.
In motoring a vehicle, power flows from the dynamometer roll
through the rear wheels into the engine, analogous to coasting
down a,hill. A Clayton water brake dynamometer is incapable
of operating this way. This motoring horsepower plus the
indicated horsepower gives the vehicle engine horsepower which
permitted EPA to evaluate the vehicle powerplant performance.
The road load horsepower vs. speed curve that was set into
the electric chassis dynamometer for these tests was identical
to the curve on a Clayton dynamometer for the same inertia
weight class. To confirm this, tests were conducted on a
Chevrolet Vega for which Clayton dynamometer test data were
available. Data on exhaust emissions and fuel economy from the
electric dynamometer tests were then compared and found to be
within the repeatability range of the Clayton dynamometer
test results.
Dilution Box: Since Rankine cycle systems are extremely sensitive
to exhaust system pressure, measurements were made with a mano-
meter of the pressure in the exhaust adapter between the car
and the dilution box. Removing .the first of the three dilution
box filters (see Figure 1) reduced negative pressure on the
vehicle exhaust to less than one-half inch Of water. All tests
were run without this first filter. For the steady state tests,
exhaust backpressure was between -.4 and -.2 inches of water.
Sampling and Analysis: The Constant Volume Sampler (CVS) unit
employed for the FTP tests had a capacity of about 400 standard
cubic feet per minute (scfm), sufficient to handle the exhaust
flow from the Carter car, which was about 300 scfm maximum.
Bag samples of the dilute exhaust/air stream were analyzed by
the standard complement of instruments: non-dispersive infrared
(NDIR) analyzers for CO and C02, a chemiluminescence (CL)analyzer
for NOx, and a flame ionizationdetector (FID) for unburned hydro-
carbons. Because the Carter fuel blend contained kerosene a heated
sample line and FID system, as described in the FTP for Diesel-
powered passenger cars, was employed. Otherwise, the heavy HC
fractions in the exhaust gas would condense and thus be lost to
analysis, leading to errors in calculating HC mass emissions. The
continuous analysis of the diluted exhaust stream with the hot
FID was the source of the hydrocarbon emission values reported
here for the 1975 FTP and steady state tests done in May. Equip-
ment problems, which would have caused an unacceptable delay,
prevented the use of the heated FID in March.
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-4-
Added Instrumentation: Several additional pieces of equipment
were used to allow evaluation of additional vehicle parameters.
Since a Rankine cycle system is more sensitive than an internal
combustion engine to ambient temperature changes, wet and dry
bulb temperatures were continuously recorded throughout the
tests. For the steady state tests, temperatures were stable
to within - 2*F during each test. For the 1975 FTP and Federal
Highway Cycle tests, temperatures were stable to within - 4*F
during each test.
Air-to-fuel ratio was determined for several steady state tests
by taking continuous samples from the raw exhaust stream. Since
HC and CO concentrations were much lower than C02 concentrations,
only CC>2 was measured to determine the air-to-fuel ratio.
Fuel consumption during steady state tests was measured with a
burette. This gave an alternative to the carbon balance method
for calculating fuel consumption.
Operating Procedures: Due to their familiarity with this unique
vehicle, Carter personnel operated it during the tests. Because
the time required to get underway following a cold start on the
Carter car was in excess of the engine startup and idle period
specified in the "75 FTP (which was developed for conventional
cars), the procedure was altered to allow the driver to begin
the first acceleration on the Federal driving cycle as soon as
steam conditions permitted, but with the exhaust sampling beginning
at the time of ignition. The time interval between the start of
ignition and the first acceleration was 43 seconds on the first
test and 48 seconds on the second test. For the hot start portion
of the tests the times were 21 and 8 seconds; For a test of a
conventional car this time interval is 20 seconds.
Results
Results of the two '75 FTP emissions tests are presented in the
following tables, with pollutant mass emissions in grams per
mile. The fuel economy for the entire test was calculated using
the carbon balance method and is expressed as miles per gallon.
The total test period is divided into three portions, with a bag
sample collected during each. The Cold Transient portion, which
includes engine startup, is in Bag 1. The Hot Stabilized portion
is in Bag.2, and the Hot Transient, including a hot startup, is
in Bag 3. The composite value for the entire test includes the
standard weighting factors assigned to each bag value.
Test No. HC CO ' NOx Fuel Economy
and Date Bag gpm , gjpm gpm miles/gallon
No. 1 1 .93 1.71 '. .44
May 9 2 .16 1.51 .37
3 .25 .70 .38
Composite .34 1.33 .39 12.7
No. 2 1 .95 1.05 .32
May 10 , 2 .25 1.16. .29
3 .25 .96 .39
Composite . .40 TTolF .33 14.9
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-5-
The improved fuel economy in the second test is attributed to
a modification in the gear shifting procedure.
It can be seen that pollutant emissions from the Carter steam
car were below the original (1976) statutory emission standards
of .41 HC, 3.4 CO and .4 NOx. Data from the individual bags
show that the cold start portion of the test creates the greatest
problem, particularly for hydrocarbons. Reduction of unburned
HC emissions during the cold start would result in considerable
improvement in the composite total HC value. It should be noted
that the car was tested at essentially "zero miles," while
the Federal certification process requires tests at 4,000 miles
and 50/000 miles.
The vehicle was not able to accelerate as rapidly as required
by the driving cycle at speeds above 20 mph, as seen in Figure 2.
As a result of this, the distance travelled while collecting
Bags 1 and 3 was 3% low. Recalculation of the mass emissions
based on the actual mileage increased the emissions about 2%
(see Table I). All pollutant emissions still met the above
statutory emission standards.
In two tests over the Federal Highway Driving Cycle, the Carter
car delivered 16.3 and 17.3 miles per gallon respectively.
For comparison purposes, the following estimates of '75 FTP
exhaust emissions and urban fuel economy data for a conventional
VW squareback with 4-speed manual transaxle are presented. These
data are based on 1973 certification results adjusted to 1975
weighting.
HC CO NOx Fuel Economy
gpm gpm gpm mpg
2.2 12 2.8 22
Highway cycle fuel economy data for the conventional VW
squareback are not available at this time.
Results of the steady state tests are presented in Tables II
through IX with pollutant mass emissions in grams per mile.
Fuel economy for the steady state tests was calculated using
both a carbon balance method arid a measured volume method
and is expressed as miles per gallon.
During March steady state emissions testing was done to
evaluate the burner, boiler, and expander performance. The
steady state road load tests (Tables IV and VI) showed the
Carter car's hydrocarbon (HC) and carbon monoxide (CO) levels
were low enough to expect the car to meet original 1976
statutory emission standards for HC and CO; nitrogen oxide
levels (NOx) however were too high. The vehicle road load curve
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-6-
was based on an estimate of the Clayton dynamometer road
load curve. Later checks showed this estimated value to be
slightly high. The excess load is expressed as a percent
grade.
For comparison purposes, a standard 1974 Volkswagen was
checked for fuel economy using the same test setup and
road load (see Table VIII). Fuel economy (mpg) of the
conventional VW was about twice as good as that of the
Carter-car.
A vehicle emissions map was also obtained (Figure 3).
The air cooled condensers were replaced with a water
cooled condenser so that power output was not limited
by condenser capacity. Fuel flow rate was manually set.
The car was then operated at several speeds (in fourth
gear) while emission samples were taken (see Tables V
and VII). The resulting emissions map, Figure 3 and
Table VII, permits evaluation of vehicle emissions and
performance under many operating conditions.
The Federal Driving Cycle was not attempted during the
March test series because the steam car experienced
some loss in power. The car was returned to Texas for
corrective action and power system modifications. The
corrective action included repairing valve seats and
replacing a crank case o-ring. Power system modifications
included installation of new piston rings, changes in
fuel/air control components and addition of finless
falme-quenching cold water tubing to reduce the-formation
of nitrogen oxides.
The Carter car was returned to EPA in May for further
testing. A repeat of the steady state road load tests'
(Tables II and III) showed an improvement in vehicle
mass emissions. HC and CO emissions were higher than
measured in the earlier tests but NOx emissions were
lower. The net result was that the car was able to meet
the original 1976 exhaust emission levels. The road
load horsepower-vs-speed curve used in these tests was
identical to the curve of a Clayton dynamometer for the
same vehicle inertia weight class.
The hydrocarbon mass emissions were lower for the heated
FID than for the cold bag sample. This lower value may be
related to the sample line and FID temperatures. Since
there was no previous work indicating an optimum sample
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-7-
line temperature, the Diesel procedure temperature, 375*F,
was used. This may have been too high a temperature for
the kerosene/gasoline blend. Hydrocarbons in the heated
FID sample may have been oxidized in the heated line,
thus reducing the concentration observed.
Differences in fuel economy between the timed volume
and carbon balance methods are small and within acceptable
test variability. Part of this variability was due to the
type of vehicle and test procedure. At steady speeds, the
Carter car continuously changes air and fuel flow to
maintain pressure, thus the fuel flow rate cycles.
Emissions samples were taken over a five minute period
to obtain an adequate sample. The fuel burette held
insufficient fuel for this length of time; therefore,
each method could have a slightly different fuel flow
rate.
The vehicle did not require additional water for the
boiler during testing.
Conclusions
The vehicle performed well in EPA tests. The mass
emissions met the original 1976 statutory emission
levels of .41 grams per mile hydrocarbons> 3.4 grams
per mile of carbon monoxide, and .4 grams per mile of
nitrogen oxides. The average composite result of the
two EPA tests was HC .37, CO 1.2, and NOx .36 grams
per mile.
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AIR
^
INLET AIR
TEMPERATURE BECORDE*
PARTICIPATE
FILTER
(ONE FILTER
REMOVED)
CVS
EXHAUST
FIGURE 1
TEST
SET UP
ANALYZER
»—HOT
F.LD.
-------
NOTE:
J-A4:-
ACTUAL
TRACE:
FIG 2a.: EPA URBAN DYNAMOMETER
DRIVING SCHEDULE
-------
tfl
NOTE/
LA4l
ACTUAL
TRACE:
RG. 2b.i EPA URBAN PYNAJAOIAETER
DRIVING SCHEDULE
-------
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TABLE I
Carter Steam Car
Exhaust Emissions & Fuel Economy
1975 Federal Test Procedure
Test No.
& Date Bag
No. 1 1
May 9
2
3
Composite
HC
gpm*
.93
.16
.25
.344
CO
gpm
1.71
1.51
.70
1 . 33
Fuel
NOx Economy
gpm mpg
.44
.37
.38
.39 12.7
• ' '• '• %-'*-v
..'Mi lea
short
2.5%
.5%
3.3%
Composite
using actual
mileage
.350; 1.35
.395
12.5
No. 2
May 10
- • 3
Composite
Composite
using actual
mileage
95
25
25
399
408
1.05
1.16
.96
1.08
1.10
.32
•29
.39
.33
.34
14.9
14.6
.4%
4%
Highway Cycle
May 8
May 9
16.3
17.3
*The improved fuel economy in the second test is attributed
to a modification in the gear shifting procedure.
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TABLE II
Carter Steam Car
Exhaust Emissions & Fuel Economy
.Steady State Modes
STEADY STATE ROAD LOAD
Exhaust Emissions
Vehicle
Speed
mph
Idle
Idle
10
10
10
10
20
20
20
20
30 ;
30
30
30
40
40
50
50
60
60
Trans-
mission
gear
N
N
First
First
Second
Second
Second
Second-
Third
Third
Third
Third
Fourth
Fourth
Fourth>
Fourth
Fourth
Fourth
Fourth
Fourth
HC
Cold FID
gpm
8.5*
6.0*
0.48 •
0.31
0.57
0.48
0.20
0.05
0.27
0.28
0.08
0.05
0.11
0.09
0.03
0.02
0.01
0.01
0.01
0.00
HC
Hot FID
gpm
6.2*
6.6*
.30
.28
.47
.48
. 12 .
. 02
.-18
.14
.04
.01
.06
.07
.01
.01
0
0
0
o
CO
gpm
30.9*
24.9*
3.37
2.56
2.49
2.59
_ 1.42
0.90
1.61
1.18
0.68
0.41
0.90
0.65
0.44
0.24
0.09
0.16
0.07
0.11
NOx
gpm
2.88*
2.76*
0.53
0.40
0.30
0.51
0.29
0.29
0.22
0.24
0.25
0.27
0.22
0 . 2.2
0.25
0.25
0.28
0.28
0.34
0.34
Fuel
Flow
gal/hr
.632
.648
1.007
0.870
0.672
0.638
1.135
1.114
0.894
0.923
1.422
1.337
1.416
1.242
1.736
1.736
2.475
2.446
3.567
3.579
Fuel Economy
Timed
Volume
mpg
9.9
11.5
14.9
15.7
17.6
17.9
22.4
21.7
21.1
22.4
.21.2
24.1
23.0
23,0
20.2
20.4
16.8
16.8
Carbon
Balance
mpg
10.5
11.8
13.7
14.2
17.1
18.4
20.9
21.8
21.8
23.8
23.4
24.7
22.8
23.7
20.0
20.9
17.4
17.4
*grams/hour
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TABLE III
Carter Steam Car
Powertrain Performance
Steady State Modes
Vapor Generator
.Expander (engine)
Vehicle Trans-
Speed mi s s ion
0
0
10
10
10
10
20
20
20
20 :
30
30
30
30
40
40 '
50
50
60
60
N
N . ;; ... .-/ ;.
First
First
Second
Second
Second
Second
Third
Third
Third
Third •
Fourth
Fourth
Fourth
Fourth
Fourth
Fourth
Fourth
Fourth
Air/Fuel
Ratio
36.2
35.0
35.0
35.0
35.6
33.9
33.9
31.9
29.5
31.8
31. 8
30.8
31.3
30.8
29.9
25.9
No data
22.7
No data
Rear
Wheel
,-:-. HP
0
-.' • •'. 0 •'.
.29
.29
.29
.29
1.00
1.03
.84
.87
2.50
'; 2.70
2.44
2.58
5.68
5.52
9.53
9.73
15.20
15.84
Outlet .
Pressure
psi*
1000
1200
750
800
950
800
7551
875
875
950
875
1050
1000
1100
975
1100
1100
1250
1300
,Temp.
; 'F*
t
775
775
955
960
810
755
955
980
800
950
965
975
800
830
915
925
980
980
980
965
RPM
1500
1850
2500
2550
1400
1350
2700
2650
1700
1800
2500
2500
1800
••'•<.. 1800
2200
2200
2800
2800
3400
3400
Pressure Temp.
Inlet Outlet
psi* "F
400
350
350
375
425
410
425
425
470
450
500
510
500
550
650
675
775
775
950
925
163
185
20
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TABLE
Carter Steam Car
Exhaust Emissions & Fuel Economy
Steady State Modes
Exhaust Emissions
vehicle
Speed
10*
9
10
20*
19
19
30*
30
30*
30
40*
40
50*
50
60*
60
Trans- Percent
mission Grade
gear
First
First
Second
Second
Third
Third
Third
Fourth
Fourth
Fourth
Fourth
Fourth
. Fourth
Fourth
Fourth
1.2
1.1
Second 1.2
1-2
1.1
1.1
1.0
.9
1.1
.9
.6
.5
.1
0
Q
0
Cold
HC
.08
.02
v02
.01
.01
.01
.01
CO
gpm
.28
.07
. 06
.06
.06
.12
.34
NOx
gpm
.90
.71
.69
.58
.68
.70
.71
*Exhaust emissions for these tests only
Fuel
Flow
gal/hr
1.104
1.002
. 830
1.448
1.390
1.128
1.755
1.654
1.679
1.503
2.168
1.952
2.746
2.551
3.625
3.235
Fuel Economy
Timed
Volume
mpg
9.1
9.0
12.1
13.8
13.7
16.8
17.1
18.1
17.9
20.0
18.5
20.5
18.2
19.6
16.6
18.5
Carbon
Balance
j- mpg
9.4
14.3
17.3
18.8
19.1
18.6
17.2
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TABLE V
Carter Steam Car
Exhaust Emissions & Fuel Flow Rates
Steady State Engine Mapping
Exhaust Emissions gm/hr
Fuel Flow.gal/hr
Fuel
Flow Rate
Nominal
2
3
4
5
HC
HC
.24
1.20
1..2.0
.72
CO
CO
.36
4.68
4.08
106.50
NOx
NOx
27,65
33. 80
21.50
45. 60
Timed
Flow
gal/hr
2.019
3.231
3.771
5.485
Carbon
Balance
gal/hr
2.127
3.448
3.750
5.455
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TABLE VI
Carter Steam Car
Ppwertrain Performance
Steady State Modes
Vapor Generator
Outlet
Expander (engine)
Vehicle
Speed
10*
9
10
20*
19
19
30*
30
30*
30
40*
40
50*
50
60*
60
Trans-
mission
First
First
Second
Second
Second
Third
Third
Third
Fourth
Fourth •
Fourth
Fourth :
Fourth
Fourth
Fourth
Fourth
Rear Wheel
HP
1.21
1.01
1.15
2.80
2.51
2.51
4.84
4.64
4.92
4.64
7.36
7.00
10.27
9.9
13.68
13.12 ;
Percent
Grade
1.2
1.1
1.2
1.2
1.1
1.1
1.0
.9
1.1
•9
.6
.5 :
. 1
0
0
0
; Pressure
psi*
750
750
900
850
800
1000
1000
1000
1150
1100
1150
, 1100
1200
1150
, 1250
1175
Temp.
*F*
1000 '••.-:."•'
1000
990 :
1000
1000
1000 ,';:;•;
1010 ,:
1000
1000
;.. 1000
: 1015
r 990
1000
1010
1010 •
. 1000
RPM
2400
2450
1425
2600
2625
1700
2500
2500
1750
1700
2200
2275
2750
2275
3400
3350
Inlet
psi*
475
450
500
525
525
650
725
680
850
825
850
840
1000
900
1000
950
Outl
240
250
260
250
260
2,70
255
270
240
280
240
265
230
270
240
270
*Exhaust emissions, data for these modes are in Table IV.
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TABLE VII
Carter Steam Car
Powertrain Performance
For Vehicle Emissions Map
jhicle Rear Wheel
Speed HP
20
30:
65
25
30
55
30
40
40
50
9
9
3
18
19
17
22
21
30
32
.00
,86
.42
, 12
.48
.40
.89
.16
V67
.60
Vapor Generator
Outlet
Pressure Temp.
1325
1040
625
1800
1575
1100
1800
14 4 a
1890
1750
910
920
930
880
870
870
960
950
980
960
Expander
Inlet Pressure
RPM psi
1150
1750
3600
1450
1700
3025
1750
2200
2275
2825
1325
1010
600
1800
1525
1040
1800
1425
1850
1725
(engine)
Outlet Temp.
*F
230
245
265
180
210
230
245
260
230
240
Fuel
Flow Rate
Nominal
2
2
2
3
3
3
4
4
5
5
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TABLE VIII
Volkswagen Type 111/113
Powertrain Performance
Vehicle
Speed
9
10
19
20
30
30
40
40
50
60
60
50*
60*
70*
Trans-
mission
First
Second
Second
Third
Third
Fourth
Fourth
Fourth
Fourth
Fourth
Fourth
Fourth
Fourth
Fourth
Percent
Grade
1.1
1.2
1.1
0.0
.9
.9
.9
.9
0.0
0.0
0.0
5.1
4.3
3 . 2
Rear Wheel
HP
1.01
1.15
2.51
2.64
4.64
4.64
7.00
7.00
9.90
13.12
13.12
28 . 63
34.48
38.17
Fuel Flow
gal/hr
.620
.424
.820
.552
.904
.746
1.060
1.050
1.500
1.905
1.923
2.907
3.565
4.020
Fuel Ecoi
mpg
14.5
23.6
23.2
36.2
33.2
40.2
37.7
38.1
33.3
31.5
31.2
17.2
16.8
17.4
*Wide-opeh throttle
1974 Volkswagen Type 111/113 (Super Beetle)
96.6- eijjaic inch, single carburetor, EGR, approximately 4000 miles on vehicle
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