73-5
An Evaluation of the Questor Emission
Control System
Thomas C. Austin
Test and Evaluation Branch
Environmental Protection Agency
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Background
At the request of representatives of the' Questor Auto-
motive Products Company a meeting was held at EPA's Ann Arbor
laboratory to give Questor the opportunity to describe their
"Reverter" emission control system to EPA. Emission data
presented at that meeting indicated that the vehicle equipped
with the Questor system could achieve the exhaust emission
levels required for model year 1976. Durability data was
preliminary but encouraging.
To validate the data presented by Questor and to ••
gharacteri.ze the.--, exhaust. emissi,pnsndur,ingLnonjLA4iidri;vang
JEPA $,esj,i-ngewas scheduled. r' . •
Vehicle Tested
The Questor "Reverter" emission control system was
installed on a 1971 Pontiac Catalina equipped with a 400
CID V-8 engine, automatic transmissipn and air conditioning.
The emission control system consists] of a non-noble reduction
catalyst sandwiched between two partial thermal reactors.
Carburetor calibration and exhaust port air injection rates
are set such that a reducing atmosphere is still present
after the exhaust gas passes through the first partial
thermal reactor. After the exhaust passes through the
NOx catalyst additional air is added to complete the
combustion of the HC and CO remaining. Exhaust gas re-
circulation (EGR) was not used.
The v.ehicle^s. "exhaust system was constructed from
double walled pipe. Air pump discharge is routed to the
rear of the vehicle and pumped into the annular cavity
surrounding the inner exhaust pipe. The air is then
heated by the hot inner pipe as it travels toward the
front of the vehicle where it is removed from the annular
cavity and injected into the partial thermal reactors at
800°F.
One feature of the Questor system was enleanment of
the mixture during high load conditions. When the vehicle
is loaded above about 10-15 rear wheel horsepower for a
period of time (about 20-40 seconds) a portion of the air
injection is switched into the intake manifold. This
enleanment does not occur during the LA4 (Federal) driving
cycle because the vehicle is not loaded highly enough for
a long enough period of time due to the stop and go nature
of the cycle. Questor representatives told us the purpose,
of the enleanment system is to both protect the catalyst from
sustained high temperatures and to improve fuel economy during
highway operation.
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At the time of our testing of the vehicle there was
approximately 4,000 miles on the system. Questor repre-
sentatives are not expecting significant catalyst durability
problems. The metallic NOx catalyst is run at- very high
temperatures (1750°F+) to eliminate lead poisoning. The
vehicle had been funning on leaded gasoline and leaded
gasoline was used during EPA testing.
A schematic of the Questor system appears in Figure 1.
Test Program
Due to other testing commitments the Questor vehicle
was only available for one day of testing. More tests
are scheduled in the future. The testing performed con-
sisted of one 1975 Federal Test Procedure and a_60 mph .
steady state cruise.._ _ Vehicle fuel consumption was. Determined
"using" b'bth carbon balance and weighing methods. A. description
"of the Federal Test Procedure is enclosed.
Test Results
Results are summarized in Table I. The gaseous emission
levels were below the Federal requirements for 1976. The
fuel consumption of 6.9 miles per gallon indicates almost
a 25% loss in fuel economy from current production vehicles
of similar weight. The exhaust gas was also tested for
formaldehyde andononly trace levels less than 005 gpm were
found. .
The emission levels measured at 60 mph were determined
after the vehicle had been at 60 mph long enough to
activate the enleanment system. Good HC and CO control
was maintained although a significant, but not total,
loss of NOx control was noticed. (The 3.15 gpm of NOx
measured at 60 mph should not be directly compared to
the .37 gpm of NOx measured on the Federal (LA4) driving
cycle because the engine loading is different.) Fuel
consumption during the 60 mph cruise was 15.8 mpg which
is comparable to, if not better than, 1972 vehicles of
similar weight and size.
Conclusions
1. The Questor emission control system can achieve the
1976 Federal emission levels at low mileage. Durability
is yet to be demonstrated.
2. The Questor system causes a considerable (=25%) loss of
fuel economy in stop and go driving.
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3. The Questor system does not adversely effect fuel
consumption during freeway operation. There is, however,
some loss in emission control during freeway operation.
4. There is potential for improving fuel consumption during
stop and go driving with further system development.
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TABLE I
Questor Emission Control System
1975 Federal Test Procedure
(all data in grams per mile)
Questor vehicle
1975 Federal
Standards
1976 Federal
Standards
HC
.15
.41
.41
CO
2.34
3.40
3.40
NOx
.37
3.1
.40
MPG
6.9
...
60 mph Steady State
(all data in grams per mile)
HC
CO
NOx
MPG
.Questor vehicle .01
10.16
3.15
15.8
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FEDERAL EMISSION TESTING PROCEDURES
FOR LIGHT DUTY VEHICLES
The Federal procedures for emission testing of light
duty vehicles involves operating the vehicle on a chassis
dynamometer to simulate a 7.5 mile (1972 procedure) or
11.1 mile (1975 procedure) drive through an urban area.
The cycle is primarily made up of stop and go driving and
includes some operation at speeds up to 57 mph. The
average vehicle speed is approximately 20 mph. Both the
1972 and 1975 procedures capture the emissions generated
during a "cold start" (12-hour soak @ 68°F to 86°F before
start-up). The 1975 procedure also includes a "hot start"
after a ten minute shut-down following the first 7.5 miles
of driving. •
Vehicle exhaust is drawn through a constant volume
sampler (CVS) during the test. ThejCVS dilutes the vehicle's
exhaust to a known constant volume fvith make up air. A
continuous sample of the diluted exliaust is pumped into
sample bags during the test. i
Analysis of the diluted exhaust collected in the sample
bags is used to determine the mass of vehicle emissions per
mile of operation (grams per mile). A flame ionization de-
tector (FID) is used to measure unburned hydrocarbon (HC)
concentrations. Non-dispersive infrared (NDIR) analyzers are
used to measure carbon monoxide (CO) and carbon dioxide (C02).
A chemiluminescence (CL) analyzer is used to determine oxides
of nitrogen (NOx) levels.
These procedures are used for all motor vehicles designed
primarily for transportation of property and rated at 6,000
pounds GVW or less, or designed primarily for transportation of
persons and having a .capacity of twelve persons or less. Each
new light duty vehicle sold in the United States in model years
1973 and 1974 must emit no more than 3.4 gpm HC, 39. gpm CO
and 3.0 gpm NOx when using the 1972 procedure. In 1975 the
standards will change to .41 gpm HC. 3.4 gpm CO and 3.1 gpm NOx
using the 1975 procedure. In 1976 the standards will be .41
gpm HC, 3.4 gpm CO and .4 gpm NOx using the 1975 procedure.
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QUGSTOR EMISSION
; COMT£OL SYSTEM
POMPS
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