74-24
Exhaust Emissions from a 53-Passenger
Lear Rankine Cycle Steam Bus
February 1974
Test and Evaluation Branch
Emission Control Technology Division
Environmental Protection Agency
-------
Background .
A steam Rankine cycle power system, designed and built by
Lear Motors Corporation, was installed in a 40-foot urban
transit coach, in a Department of Transportation sponsored
program to demonstrate the potential of external combustion
power systems in city bus service.
After the installation of the steam power system and
a period of shakedown, development, and optimization,
the bus was sent from Lear Motors in Reno, Nevada to California.
There it was tested by the California Air Resources Board and
easily met the California clean air standards. The bus was
then used by the San Francisco Municipal Railway, the transit
system of that city, in revenue service for limited service
testing and to determine passenger acceptance. The bus performed
well over even the steepest routes and received good public
acceptance. (Reference 1)
Arrangements were made with Lear Motors for exhaust emissions
tests at the Office of Mobile Source Air Pollution Control
(OMSAPC), Ann Arbor laboratory. The tests of the steam bus
reported herein were conducted over a two week period in
October 1973.
The emissions tests were conducted by the Test and Evalua-
tion Branch of the Emission Control Technology Division as
part of a continuing effort to stay abreast of alternative power
systems development and assess the emission control potential
of such systems. OMSAPC provided transportation of the bus
from Reno, Nevada to the Ann Arbor laboratory. Lear Motors Corp.
provided personnel to operate the bus and interpret engine
parameter data.
Vehicle Description
The bus chosen for this project was a CMC model T6H 5305A
built by General Motors Coach Division. The engine usually
installed in this 53-passenger bus is a 426 cubic inch dis-
placement (CID) Detroit Diesel supercharged Diesel V-6 internal
combustion engine. For heavy duty service such as in San
Francisco a 567 CID V-8 would usually be used.
-------
The Lear Motors steam rankine cycle power system installed
in the bus is described in References 1,and 2 at the end of
this report. Briefly, the power system includes a monotube
vapor generator that provides superheated steam for a turbine
expander. Turbine power output goes through a reducing gearbox
to the four-speed automatic transmission originally installed
in the bus. Diesel number 1 is the fuel. The engine, including
condensers, was installed in the rear of the bus in the normal
engine compartment. Test instrumentation was neatly packaged
and occupied only two seats at the rear of the bus. Only a
few additional gauges and switches were required by the vehicle
operator.
The curb weight of the stock bus is about 20700 pounds. The
bus as tested with the steam power system and instrumentation
installed weighed about 22775 pounds. All testing was done
with an inertia weight of 28500 pounds to simulate the weight
of the standard.bus fully loaded. This also duplicated the test
weights of the bus during its California tests.
Test Program
The Lear bus arrived at the ^Ann Arbor laboratory on Monday
evening, October 15, 1973, and was used for demonstration through
Wednesday. Vehicle preparation and facility checkout took several
days. Testing started on October 23 and continued through
October 29. However, due to several vehicle problems, only a
small number of tests were completed. These were principally
a modified version of the Federal 13-mode heavy duty Diesel
engine test procedure. This modified procedure is similar to
the heavy duty Diesel engine test procedure developed by the
California Air Resources Board (GARB) and the Engine Manu-
facturers Association. This procedure, which will be referred
to as the Federal 13-mode procedure, is described in SAE paper
number 700671, and the Federal Register of November 15, 1972,
Vol. 37, Number 221, Part II.
For these tests a heavy duty electric chassis dynamometer
was used which had motoring capability and permitted both speed
and torque control. The dynamometer is equipped with large
diameter (40") rolls to minimize slippage.and tire loss problems.
Rear wheel horsepower was measured and engine brake horsepower
was then calculated to provide the basis for determining brake
specific emissions.
-------
The heavy duty Diesel procedure is a steady state procedure
for testing a Diesel engine on an engine dynamometer with engine
load as the operating variable at each of two engine speeds,
"rated" and "intermediate". The load is varied from zero to
maximum torque available at each of these two engine speeds,
in steps of 25% of maximum torque. Three idle periods are
interspersed among these load points, for a total of 13 operat-
ing modes. Rated speed is self-explanatory: the maximum allow-
able continuous engine speed. Intermediate speed is defined
in the procedure as "...peak torque speed or 60% of rated speed,
whichever is higher". For the steam power system, 57,000 and
62,000 rpm were selected as the intermediate and rates speeds,
respectively, since these were the turbine speeds used when
the bus was tested in California. These were chosen since
they would give road speeds of 30 mph (3rd gear) and 50 mph
(4th gear) respectively, these speeds corresponding to city
and inter-city cruise speeds.
The 13-mode procedure calls for continuous analysis of
exhaust pollutant concentrations and measurements of engine
fuel and air consumption rates for calculation of exhaust
pollutant mass emissions. However, for simplicity and ease
of calculation in our tests of the steam bus, the Constant
Volume Sampling technique (CVS) was also employed. In the
CVS method a positive displacement air pump pulls a constant
volume stream consisting of all the engine exhaust plus
dilution air. From this mixture a small sample is pumped
into an impermeable Tedlar plastic bag for analysis at the
end of the test period. The product of pollutant mole con-
centration times pollutant density times constant volume flow
rate, in appropriate units, gives pollutant mass emissions.
The sample bags and raw exhaust were analyzed using the
usual array of instruments: unburned hydrocarbons (HC) were
measured with a flame ionization detector (FID), CO and C02
with non-dispersive infrared (NDIR) analyzers, and nitrogen
oxides (NOx) with a chemiluminescence (CL) device. Fuel flow
was measured with a Flotron mass flow meter.
The raw exhaust sample probes were located in each exhaust
duct. Suitable plumbing was installed to permit sampling from
either duct. Manometer taps were also located in each exhaust
duct to monitor backpressure. Throughout the testing exhaust
backpressure was held to less than plus or minus 5 mm of water
(t.2 in.).
-------
Since the expected large exhaust mass flow rates, 1500
SCFM, were well beyond the capabilities of the laboratory
CVS unit, it was connected to only one side of the vehicle.
New procedures were developed to calculate total mass
emissions. By a carbon balance method, the CVS mass emissions
can be used to calculate the amount of fuel they represent.
Therefore, the remainder of the fuel and its combustion products
go out the opposite exhaust. Thus by a procedure similar to
the heavy duty gasoline procedure the exhaust mass flow rate
can be calculated and since the emission concentrations are
measured in each exhaust duct, the mass emissions going out
the non-CVS side can be calculated.
Early in the testing of the steam bus it became evident
that it would be impossible to obtain stable emission levels
at stable preselected power settings due to the nature of
the engine design and its controls. Fuel is supplies pro-
portionally to air flow to maintain steam pressure between
selected limits. However, apparently slightly too much fuel
was supplied; thus raising the temperature and pressure to
their operating limits. This caused a fuel/air cutback and,
when the pressure dropped sufficiently, a fuel/air increase.
This was seen as an 80 second cycling in the emission con-
centrations and cycling in the fuel flow rates during all
tests. Thus neither the emission mass flow rates, emission
concentrations, nor fuel flow rates were at the required constant
levels.
The Flotron as instrumented gives errors in total fuel
consumed during cyclic operation. By comparing the ratio of
fuel measured by CVS carbon balance to total fuel measured
by the Flotron, an estimate of the fuel error introduced and
fuel split versus horsepower was made. The right exhaust
sometimes showed a slightly higher (no greater than 15'%) emission
concentration than the left side, particularly at higher power
settings.
Therefore the procedure for calculation of emissions was
altered. Emissions were assumed to be directly proportional
to fuel flow rate; thus emissions on the non CVS side were
equal to emissions on the side connected to the CVS times the
ratio of fuel used on each side.
-------
Major mechanical problems were encountered which interrupted
testing and limited the total number of tests. The feedwater
pump was changed once in testing. The water turbine* failed
on October 23 during a bus route test. During this test there
was a higher than desired load of the dynamometer. A second
water turbine failure on October 26 necessitated using an
organic* turbine wheel for the final tests. Surprisingly, it
gave greater power.
Desired load and engine speed settings were calculated prior
to each test. However, these were not always readily attained
and when these values were adjusted for dynamometer friction
losses, rear wheel motoring losses, transmission efficiency, and
converter efficiency, they differed from the 25, 50 and 75% hp
values. These corrections were nearly the same for all tests as
were the observed maximum horsepowers.
The corrected horsepower values were used to interpolate
between the fuel-adjusted CVS emission numbers to find the
desired 2, 25, 50 and 75% hp values. These values were weighted
together to obtain overall brake specific emissions.
Tests of a "Baseline Bus"
The Test and Evaluation Branch tested a Diesel bus prior
to the steam bus in order to check out instrumentation and
establish baseline emissions with which emissions from the
steam bus could be compared. Only a few tests were completed
due to equipment problems which delayed testing.
The baseline bus was a CMC T6H 4523A 45-passenger city bus
powered by a Detroit Diesel 426 CID supercharged V-6 Diesel
engine. This vehicle is identical to the T6H 5305A except that
it is 5' shorter and weighs less, at 19500 pounds. The bus was
manufactured in May 1973 and arrived with only 670 miles on the
odometer. This vehicle was obtained through the courtesy of
Mr. John Hubbard of GM Truck and Coach Division where it is to be
an engineering vehicle. Mr. Richard Schultz of GM Truck and Coach
provided technical assistance. Since the engine was new, add-
itional mileage was accumulated during instrumentation setup and
checkout. About 200 additional miles were accumulated prior to
testing. The dynamometer inertia weight setting was the same as
for the steam bus, 28500 pounds. For the 13-mode test the converter
was locked up through the use of a bypass line on the torque
converter, thus eliminating converter slip. The Lear bus was not
locked up during testing, therefore, the test results were ad-
justed to include the converter losses.
Gee Notes 1 and 2 on page 10
-------
Operating conditions included a simulation of the Federal
13-mode heavy duty procedure, and the Ann Arbor-1 (AA-1)
Urban Bus Cycle.
The AA-1 cycle is a speed versus time trace generated in
the summer of 1971 by attaching a fifth wheel to one of the
buses of the Ann Arbor Transportation Authority. The cycle
is not an official test cycle, but rather is used as an
experimental tool for comparing buses. The cycle consists of
26 start/stop modes, and the 5.4-mile route requires 29.5 minutes
to complete, for an average speed of about 11 mph. The maximum
speed on the cycle is 38 mph.
The procedure for the 13-mode test was to establish the
desired engine speed by using the dynamometer to control
vehicle speed. At this speed the load is controlled by the
vehicle throttle setting. Bag samples of the diluted exhaust
gas were taken at 0%, 25%, 50%, 75% and 100% of the maximum
power at the chosen engine speed. The idle modes were run
with the transmission in Neutral. Each mode was maintained
for three minutes to allow time for an adequate sample to be
taken. It had previously been determined that 1200 rpm and
2000 rpm were the desired intermediate and rated speeds,
respectively, for the Detroit Diesel 426 engine in the bus.
These corresponded to speeds of 27 mph and 45.5 mph with the
converter in lockup. The raw exhaust concentration, air flow,
and fuel flow rates were constant for each test.
To develop a valid dynamometer road load for the AA-1
bus route, and steady state tests, the CMC calculated road
load data for the T6H 5305A was used to obtain steady state
road load data. These conditions were duplicated on the chassis
dynamometer and a road load curve, Table VIII, was developed.
Results and Discussion
Results of the emissions tests on the steam bus are
presented in the Appendix in Tables I through V, and on
the baseline Diesel-engined bus in Tables V and VII. Emissions
of C02 are included to indicate fuel consumption. The fuel
economy figures in the tables were calculated by a carbon balance
equation from the mass emissions of HC, CO and C02. Rolling
resistance data on the buses are presented in Table VIII. A
schematic of the test setup is shown in Figure 10.
-------
Mass emissions from the 13-mode tests on the steam bus
are presented as grams per hour in Tables I, II, and III.
Between the tests on October 25 and October 29, the turbine
wheel type was changed and the air-fuel ratio was adjusted
to a more optimum value. Brake specific emissions were cal-
culated using the equation in Table I.
Using the brake specific emissions from Tables I, II, III
and VI the following composite brake specific emissions were
calculated:
Grams Per Brake Horsepower Hour
Steam Bus (10-25)
Steam Bus (10-25)
Steam Bus (10-29)**
Diesel Bus (10-15)
'77 Cal. Std.
HC
.5*
.3*
.4*
1.2
CO
2.7
2.3
2.0
7.4
25
NOx
2.9
3.2
1.9
11.8
8.4 (CVS)
HC+NOx
* Not heated FID
** Organic turbine wheel
Since the heated FID used on the CVS-diluted exhaust was not
operational during all tests on the steam bus, the CVS bag
hydrocarbon concentrations were used. When the FID was used,
it read hydrocarbon values approximately thirty percent greater
than were measured in CVS bag sample. The steam bus control
system shuts off the burner during idle and thus there is no
fuel consumption during stops. This does not sacrifice vehicle
acceleration performance since the boiler pressure is maintained
at idle and the recovery is instantaneous. The burner relights
as required to maintain pressure. The pressure can be held up
to 10 minutes without relighting. During the five minute idle
modes the burner relighted about half the time. This was evi-
denced by the continuous emissions traces and the higher fuel
consumption in modes 1, 7 and 13 (Tables I, II, III).
The steam bus emissions tabulated in Tables I, II and III are
plotted in Figures 4,5,6 and 7. The trends were as expected -
CO, C02 and NOx increased with horsepower, HC levels did not
change. Usually the organic turbine wheel test showed better
performance. Also, this wheel produced more horespower.
-------
During identical tests at the GM Technical Center the
following week, similar results were obtained (Ref.3). The
engine, however, operated differently, producing little or
no cycling during the 13-mode tests. Maximum measured rear
wheel horsepower was the same. This difference was probably
due in large part to additional adjustments to the air-fuel
ratio.
Although the Diesel bus emissions were considerably higher
than the steam bus emissions, the CO emissions are misleading.
The Diesel bus had been used less than 15 hours when tested.
These emissions were nearly identical to those from the dura-
bility engine (used in the Federal Heavy Duty certification
procedure) at 0 hours as shown in Table VII. Under continued
use this engine gave 30% lower CO emissions at 125 hours. This
downward trend continued with further usage.
The vehicle fuel consumption plotted in Figure 8 shows
that fuel consumption was appreciably less with the organic
fluid turbine wheel than with the steam turbine wheel. Figure 9
shows that fuel consumption on the Diesel bus was about 1/3
as much as on the steam bus.
Steady state fuel economy in miles per gallon and emissions
are given in Table IV. These results were similar to those
achieved in testing the bus at the GM Proving Ground and Tech-
nical Center (Ref.3). GM tests for fuel economy at both the
test track and Technical Center were within .25 mpg of the EPA
results at all speeds. These fuel economy results are about 20%
better than the results achieved during tests in California a
year ago (Ref.l). Also, the steam bus achieved an average
emission improvement of 5.7% for HC, 70% to 40% for C02 and
78% for NOx. This is a considerable improvement over a vehicle
whose engine easily met 1974 standards. In addition, the steam
bus meets the 1977 California HC, CO and NOx standards. Some
important cautions must be observed however: 1) although it
has considerable mileage the steam bus is a first generation
demonstration model; considerable improvements in relaibility
and fuel economy are necessar-, 2) the certification results for
the Diesel engine show that CO emissions were appreciably lower
after additional use, and 3) 60% of the Diesel CO emissions came
at intermediate speed and full power, and therefore might not
be representative of typical engine performance.
-------
Emissions from the steady state cruise modes on the steam
bus are listed in Table IV as grams per hour and grams per mile
at horsepowers selected to duplicate the vehicle road load. Fuel
economy ranged from 1.3 to 3.2 miles per gallon and was fairly
constant from 30 to 50 mph. Fuel economy was calculated by the
carbon balance method.
The Ann Arbor-1 bus route was run as a hot start only. The
road load curve as listed in Table VIII, is based on GM
computations derived from actual testing of similar vehicles.
The values in columns 1 and 3 are the horsepower required at
the engine to drive the vehicle at the steady state speeds.
The values in columns 2 and 4 are horsepower measured at the
rear wheels with corrections for driveline, tire and dynamometer
losses. Results for both buses are given in Table V and
summarized below:
HC gm/mi CO gm/mi NOx gm/mi MPG
Steam bus* 3.3 7.0 8.9 1
Diesel bus avg. 6.2 14 31.5 4.6
*Incomplete test
Conclusions
These tests of the Lear steam and a GM Diesel bus on a
chassis dynamometer correlated well with previous tests on
each. For the steam bus the results compared well with testing
by the California Air Resources Board and GM/ The Diesel bus
test results were comparable to the engine certification data.
Both vehicles were clean, easily meeting current standards.
The steam bus was appreciably cleaner and met 1977 California
standards, however, the Diesel bus fuel economy was approximately
three times better than the steam bus.
-------
10
REFERENCES
1. "California Steam Bus Project Final Report," January 1973,
Assembly Office of Research, California Legislature.
2. "Exhaust Emission Tests for the California Steam Bus
Development and Demonstration Project CAL MTD-13,"
October 1972, California Air Resources Board, Air
Resources Laboratory.
3. GM Research Laboratories letter dated November 15, 1973,
to Lear Motors Corporation.
NOTES
1. Water Turbine Wheel - Lear Motors Corporation Supersonic
turbine wheel designed for steam service.
2. Organic Turbine Wheel - Lear Motors Corporation Subsonic
organic fluid turbine wheel. This wheel was utilized to
complete the test program after the water wheels failed.
The organic wheel operates off design due to the nozzle
and working fluid mismatch.
-------
REFERENCES
1. "California Steam Bus Project Final Report," January 1973,
Assembly Office of Research, California Legislature
2. "Exhaust Emission Tests for the California Steam Bus
Development and Demonstration Project CAL MTD-13,"
October 1972, California Air Resources Board, Air
Resources Laboratory
3. GM Research Laboratories letter dated November 15, 1973,
to Lear Motors Corporation.
-------
APPENDIX
-------
4-.1 11L1.1-
lJ—L.i-i i-
|_L ;.Ill L LL
__!_U-U 1.1 L
i i i i , i i
-------
HC
/JO
/oo
I
6T 7,000 RPM -\JATER. WHEB-
A- r7,000 RPt*\ - ORGANIC
/?PA» -ORGANIC
X
o
o
X
o
X
A O
n
r/GURE ?~ HC - HP
-------
CO
-------
,340 K
300K
X
o
x °n
o
K
X
o
X= 57,OQO RPI^\- WATER WHE£V_
= 6^000 RPf^-6R«f^N\C WHCEU
ao vo
toe,
6- CO * HP
-------
X
X - S-7.OOO /9PAO -WATT^ W//£V=2- '
/ o
O *• 6^,1
P • 6*,OOO
0 <>
/so A D
"• A
FIGURE'7-A/0« ^ UP
-------
FUEL
/O
o
X
X-S7,
a-6,3,000 Rp/n -w/*7-£/e
A -S"l OOO RF>M -
D :6},
zoo
ISO
/OO
VO
60
8O
100
/VO
FIGURE 8 - FUEL USAGE
-------
300
FMEL
USAGE
ISO
/OO
30
is-
£0 80
FIGURE S-rUELL USAGE: ^ HP
-------
TABLE I
53-Passenger Steam Rankine Cycle Bus Mass Emissions
Federal Experimental 13-Mode Procedure
MODE % POWER HORSEPOWER TURBINE RPM HC gm/hr* CO gm/hr CO2 gm/hr NOx gm/hr Lbs/hr
1 Idle 0 0 14.3 12.0 3,050 8.8
2
3
4
S
6
2%
25%
50%
75%
100%
2.0
25.6
51.2
76.8
102.4
8
9
10
11
12
13
Idle
2%
25%
50%
75%
100%
Idle
2.0
25.6
51.2
76.8
102.4
Brake specific emissions *»
HC
CO
NOx
.5
2.7
2.9
gm/Bhp-hr*
gm/Bhp-hr
gm/Bhp-hr
57,000
57,000
57,000
57,000
57,000
0
62,000
62,000
62,000
62,000
62,000
0
r (pollutant x
39.5
31.5
21.6
26.3
10.8
8.5
37.0
15.6
21.8
30.3
11.4
20.0
weighting
73.0
67.7
76.4
129.1
228.5
6.3
82.6
63.7
92.3
160.9
379.1
17.6
factor)
73.0
67.7
76.4
129.1
228.5
70,400
96.700
132,300
155,000
215,500
48.0
73.0
113.4
160.6
298.1
~Z(measured BMP x weighting factor)
330
82.6
63.7
92.3
160.9
379.1
76,400
114,400
143,600
173,600
246,700
53.8
94.3
129.6
175.7
346.0
5,780
w.f.
w.f.
3.7
Lbs/hr
2.2
49.4
67.8
92.7
108.6
151.0
.3
53.6
80.1
100.6
121.7
173.0
gal/hr
.3
7.3
10.0
13.6
16.0
22.2
.0
7.9
11.8
14.8
17.9
25.5
4.1
.6
.2 x avg. idle for idle mode
.08 power modes
*HC data based on CVS bag sample. A heated FID sample would give higher values.
-------
TABLE II
53-Passenger Steam Rankine Cycle Bus Mass Emissions
Federal Experimental 13-Mode Procedure
MODE % POWER HORSEPOWER TURBINE RPM HC gm/hr* CO gm/hr C02 gm/hr
1 Idle 0 0 16.9 17.7 5,280
2
3
4
5
6
2%
25%
50%
75%
100%
2.0
25.6
51.2
76.8
102.4
8
9
10
11
12
13
Idle
2%
25%
50%
75%
100%
Idle
2.0
24.6
49.3
74.0
98.6
0%
57,000
57,000
57,000
57,000
57,000
62,000
62,000
62,000
62,000
62,000
34.9
8.0
2.1
1.5
5.9
2.2
18.6
5.5
6.6
9.2
9.1
12
77.6
44.9
76.7
124.8
296.0
75,900
121,900
147,400
183,700
238,000
52.7
94.9
131.8
197.9
359.5
8.4
540
54.5
47.3
101.1
162.7
157.0
13,500
116,600
155,900
189,600
191,000
65.6
103.8
160.7
221.0
219.0
NOx gm/hr
3.8
52.7
94.9
131.8
197.9
359.5
0
65.6
103.8
160.7
221.0
219.0
Lbs/hr
3.8
53.3
85.4
103.2
128.7
166.8
.4
9.5
81.6
109.2
132.8
133.8
gal/hr
.6
7.8
12.6
15.2
18.9
24.6
.1
1.4
12.0
16.1
19.6
19.7
17.1
6,070
5.1
4.3
.6
Brake Specific Emissions
HC .3
CO 2.3
NOx 3.2
gra/Bhp-hr*
gm/Bhp-hr
gm/Bhp-hr
*HC data based on CVS bag sample, a heated FID would give higher values.
-------
TABLE III
53-Passenger Steam Rankine Cycle Bus Mass Emissions
Federal Experimental 13-Mode Procedure
MODE % POWER HORSEPOWER* TURBINE RPM HC gm/hr** CO gm/hr CO- gm/hr NOx gm/hr Lbs/hr*** gal/hi***
2
3
4
5
6
2%
25%
50%
75%
100%
2.6
31.9
63.9
95.8
127.7
8
9
10
11
12
2%
25%
50%
75%
100%
2.8
34.5
69.0
103.6
138:1
57,000
58,000
58,000
58,000
60,000
62,000
62,000
62,000
62,000
62,000
13
46.6
17.2
9.2
36.0
108.4
5.7
35.9
7.6
0.0
4.4
14.6
8.3
107.8
73.4
74.3
176.1
411.3
65,400
98,600
125,600
172,200
211,700
42.9
72.3
108.7
170.4
205.2
5.2
126
79.7
31.6
35.9
112.1
223.2
69,500
96,400
129,300
172,100
220,600
47.6
71.6
121.9
188.7
247.6
45.0
69.1
88.0
120.7
148.8
.1
48.8
67.5
90.5
120.5
154.6
6.8
10.2
13.0
17.8
21.9
.0
7.2
9.9
13.3
17.8
22.8
7.3
.9
.0
Brake Specif Emissions
HC .4 gm/Bhp-hr*
CO 2.0 gm/Bhp-hr
NOx 1.9 gm/Bhp-hr
*0rganic turbine wheel
**HC data based on CVS bag sample,
***Diesel no. 1 6.79 Ibs/gal
a heated FID sample would give higher values.
-------
TABLE IV
53-Passenger Steam Rankine Cycle Bus Mass Emissions
Steady State Modes*
grams/hr
MPH
10
20
30
40
48
HORSEPOWER TURBINE RPM GEAR
6.3
17.2
32.5
63.7
87.7
46,000
54,000
54,000
54,000
64,000
1
2
3
4
4
HC gm/hr
29.1
29.7
32.9
10.7
15.0
CO gm/hr
81.6
61.7
86.9
59.1
101.0
CO- gm/hr
75,100
87,400
92,900
122,500
153,400
NOx gm/hr
55.1
40.0
79.5
115.4
158.4
grams/mile
MPH
10
20
30
40
48
HORSEPOWER MILES/GAL HC gm/mi CO gm/mi CO2 gm/mi NOx gin/mi
6.3
17.2
32.5
63.7
87.7
1.3
2.2
3.1
3.2
3.0
2.9
1.5
1.1
.3
.3
8.1
3.1
2.9
1.5
2.2
7,510
4,370
3,000
3,060
3,200
5.5
3.3
2.6
2.9
3.3
•Organic turbine wheel
-------
TABLE V
Ann Arbor Bus Route Mass Emissions
grams/mile
DIESEL rVS DATE
HC**
CO
CO.
NOx
MPG***
10-16
10-16
10-16
10-17
10-17
Diesel Bus Average
Steam Bus 10-23*
5.1
5.2
11.5
4.9
4.3
6.2
3-3
14.9
14.3
14.5
11.5
14.6
14.0
7.0
2,004
1,996
2,194
2,044
2,156
2,079
9,060
30.1
30.4
27.0
33.1
37.0
31.5
8.9
4.8
4.8
4.3
4.7
4.4
4.6
1.0
*Steam bus turbine wheel failed, test stopped at 4.95 miles.
**For Diesel bus this is heated continuous sampling line data. For
steam bus it is CVS result - heated continuous sample estimated
to be 304 higher
***Diesel no. 1
-------
TABLE VI
45-Passenger Diesel Bus Mass Emissions
Federal Experimental 13-Mode Procedure
MODE % POWER HORSEPOWER TURBINE RPM HC gm/hr CO gm/hr
gm/hr NOx gm/hr Lbs/hr* gal/hr*
2
3
4
5
6
2%
25%
50%
75%
100%
2.3
28.9
57.8
86.8
115.7
8
9
10
11
12
2%
25%
50%
75%
100%
3.2
40.1
80.3
120.4
160.6
550
1,200
1,200
1,200
1,200
1,200
550
2,000
2,000
2,000
2,000
2,000
20.0
57.0
47.9
46.
46,
.7
.9
61.9
21.1
95.7
89.4
92.4
87.5
128.1
13
20.6
35.7
122.6
59.5
42.6
79.1
3396.0
39.9
123.2
82.5
75.0
53.3
988.0
37.8
4,950
45.0
12,240
21,540
33,500
48,280
65,790
4,550
28,820
45,070
59,510
88,400
108,930
81.9
180.8
497.8
972.0
1007.6
46.9
185.7
444.0
787.0
1797.0
2058.0
4,750
46.2
3.5
8.8
15.2
23.6
34.0
49.9
3.3
20.5
31.8
41.9
62.1
77.6
3.4
1.2
2.2
3.5
5.0
7.4
3.0
4.7
6.2
9.1
11.4
.5
Brake Specific Emissions
HC 1.2 gm/Bhp-hr
CO 7.4 gm/Bhp-hr
NOx 11.8 gm/Bhp-hr - Diesel procedure
8.4 gm/Bhp-hr - CVS results
•Diesel no. 1 6.79 Ibs/gal
-------
TABLE VII
Heavy Duty Emissions
Standards HC CO NOx HC + NOx
1974 Federal &
California 40 16
1975-76 California 30 10
1977 California 25 5
Steam Bus 10-25 .5* 2.7 2.9 3.4
10-25 .3* 2.3 3.2 3.5
10-29** .4* 2.0 1.9 2.4
Diesel Bus 10-15 1.2 7.4 11.8 13.0
6V71N(2V)C60
Diesel Engine (Durability test)
1974 Certification Data
6V71N92V)C60 0 hours 7.3 14.3
125 hours 4.1 13.6
1000 hours 2.7 14.9
Certification
Engine 125 hours 5.2 12.6
125 hours 4.5 11.2
*not heated FID
**organic turbine wheel
-------
TABLE VIII
Bus Horsepower Requirements*
Steam Bus 28,500 Ib. Diesel Bus 26,750 Ib.
MPH Road HP (cal) Dyno HP Road HP (cal) Dyno HP
10 5.7 5.0 9.2 9.1
20 14.6 13.6 19.2 18.2
30 28.8 28.5 41.0 38.8
40 50.3 53.6 53.2 52.9
*Driveline and rear wheel hp losses are included in dyno hp and are determined
by motoring vehicle. This dyno hp is also corrected for transmission losses.
The steam bus had radial tires, the Diesel bus had bias tires. When the steam
bus is equipped with bias tires, its hp requirements are almost identical to
the Diesel bus.
------- |