71-30
    Exhaust Emission Analysis of the
Williams Research Gas Turbine Volkswagen
                May 1971
           Leonard D. Verrelli
Bureau of Mobile Source Pollution Control
         Office of Air Programs
     ENVIRONMENTAL PROTECTION AGENCY

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Vehicle Tested
The Williams Gas Turbine, 131-Q, regenerative turbine auto-
motive engine was mounted in a 1965 Volkswagen squareback
test bed.  The engine utilizes a two stage turbine to
develop 70 horsepower.  It incorporates the standard VW
automatic transmission coupled to the engine through a gear
reduction system.  Non-leaded gasoline was used as fuel for
these tests.

Test Conducted
The standard 1972 Federal test procedure using the LA 4-S4
driving cycle with constant volume sampling was used.

The 1200 cfm CVS used for this test was modified slightly
by blocking off the CVS filters and drawing dilution air
from the room with mixing occurring at the vehicle exhaust
outlet.

Oxides of nitrogen were measured using both the wet chemical
modified Saltzman technique and the chemiluminescence
instrument.  Carbon monoxide was measured using non-dispersive
infrared and hydrocarbons were determined using both the
cold and hot flame ionization detector.  Concentrations of
all pollutants were measured in the CVS bag and hydrocarbon
concentration was monitored continuously in the raw exhaust
using the hot flame ionization detector.

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                          - 2 -

Emission Results

The normal practice of subtracting the concentration of the

background hydrocarbons in the dilution air from the hydro-

carbon concentration measured in the CVS bag could not be

used in this study.  When sampling from low emission

vehicles the hydrocarbons in the dilution air can contribute

a major portion of the total hydrocarbons and the straight

subtraction correction is no longer rigorous.  Since the

volume flow of the engine was known an alternate more

correct calculation procedure could be used.


The concentration  (Ct) of the diluted sample in the CVS bag

can be expressed as follows:

                 Ct = Ce i * Cb IS
                         vt        vt

Where :

    Ct = concentration of total sample in bag

    Ce = concentration of integrated undiluted exhaust
         volume

    Cb » concentration of background contaminant dilution
         air

    Vt = volume of total sample (exhaust plus dilution air)

    Ve = volume of exhaust


Equation (1) can be rearranged solving for concentration

of exhaust  (Ce) :

                               Vt - Ve  Vt       (2)
                 r>  — Yr«j_ _ /""*-  *•    "*    •      ' '
                 Ce =

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                          - 3 -


The weight of emission (gm/mi)  of each pollutant is obtained


from:


    W = K Ce
        Where:  K = constant relating weight of emission
                    to volume of exhaust per mile


              Ve  = volume of exhaust per mile
Four LA 4-S4 tests were run, there was one aborted test


because of a leaking exhaust manifold.  There is some


question to the validity of test #1 due to suspected sample


contamination.



In Table 1 comparisons are made of all three tests using


the 1972 Federal test procedure.  Hydrocarbons in tests #2


and #3 are consistent, but in test #1 the value is consider-


ably higher possibly reflecting the hydrocarbon contamination


mentioned above.  Carbon monoxide data is inconsistent, and


nitrogen oxides also show a slight inconsistency.
                                 *


In keeping with report policy for tests such as these


oxides of nitrogen will be reported as NO2 and an overall


value will be arrived at by averaging two sets of data.



Conclusions


By averaging two sets of data it was determined that the


test vehicle did meet the 1975 standards; however, it should


be noted that some slight inconsistencies do exist.

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                          - 4 -



Because a new combustor design had been incorporated in the



engine it was unadvisable at this time to perform a larger



number of tests.  Until such a series of tests can be



performed to substantiate the data collected during this



short test, a positive determination of emission levels



cannot be made.






The driveability of this turbine car did not compare to a



conventional internal combustion engine vehicle.  Very



little engine retardation was evident; acceleration was



smooth but not rapid.

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                          Table  1


                 1972 Federal Test Procedure

HC gpm
CO gpm
CO 2 gpm
NO gpm
NO 2 gpm
Test #1*
12-1448
.89
1.78
1086.5
1.44
2.21
Test #2
12-1449E
.36
5.4
1094.5
1.55
2.30
Test #3
12-1455
.32
3.6
988.4
1.27
1.95
Average of tests #2 and #3:

 HG gpm          CO gpm          NO2 gpm             NOX**

   .34             4.5             2.12             1.81


NOX corrected for Humidity:

     Test #1               Test #2              Test #3

       1.92                 1.97                 1.65
gpm indicates calculated mass in grams per mile.
* not used in calculations because of possible effect from
  the sample contamination on emissions.

** NOX corrected for humidity.

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