EPA-AA-TAEB 75-18
Exhaust Emissions and Fuel Economy from a
Volvo Three-Way Catalyst Prototype Vehicle
March 1975
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Environmental Protection Agency
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Background
In its continuing interest to keep abreast of technological develop-
ments in the area of emission controls, the Environmental Protection
Agency requested Volvo of America Corporation to allow EPA to perform
emissions testing on a prototype Volvo fitted with their three-way-
catalyst system (TWC). Volvo agreed and sent a vehicle from Sweden
which arrived in Ann Arbor on November 8, 1974. The catalyst had
4000 miles accumulated on it and had been tested for emissions prior
to shipment; results indicated that emissions levels were below the
1977 Federal Emissions Standards of .41 grams per mile hydrocarbons
(HC), 3.4 grams per mile carbon monoxide (CO), and 2.0 grams per mile
oxides of nitrogen (NOx).
The Environmental Protection Agency receives information about
many systems which appear to offer potential for emission reduction
or fuel economy improvement compared to conventional engines and
vehicles. EPA's Emission Control Technology Division is interested in
evaluating all such systems, because of the obvious benefits to the
Nation from the identification of systems that can reduce emissions,
improve economy, or both. EPA invites developers of such systems to
provide to the EPA complete technical data on the system's principle
of operation, together with available test data on the system. In
those cases in which review by EPA technical staff suggests that the
data available show promise, attempts are made to schedule tests at
the EPA Emissions Laboratory at Ann Arbor, Michigan. The results
of all such test projects are set forth in a series of Technology
Assessment and Evaluation Reports, of which this report is one.
The conclusions drawn from the EPA evaluation tests are
necessarily of limited applicability. A complete evaluation of the
effectiveness of an emission control system in achieving performance
improvements on the many different types of vehicles that are in
actual use requires a much larger sample of test vehicle than is
economically feasible in the evaluation test projects conducted by
EPA. For promising systems it is necessary that more extensive test
programs be carried out.
The conclusions from an EPA evaluation test can be considered
to be quantitatively valid only for the specific test car used,
however, it is reasonable to extrapolate the results from the EPA
test to other types of vehicles in a directional or qualitative
manner, i.e., to suggest that similar results are likely to be
achieved on other types of vehicles.
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Vehicle System Description
The vehicle tested was a 3-way catalyst equipped Volvo prototype,
with a 4-cylinder 130 cubic inch (2130 cc) engine and automatic trans-
mission. The engine, which employs an overhead camshaft and cross-flow
aluminum head (unlike the current U.S. version) and Bosch continuous
flow fuel injection, is not currently sold in the United States.
The emission control system consists of a 3-way catalytic converter
and Lambda-sond system (an oxygen sensor in the exhaust upstream of
the converter). The single catalytic converter oxidizes HC and CO and
reduces NOx at the same time, providing the composition of the exhaust
gas remains within a narrow range. The required close control of
engine air-fuel ratio is achieved by using the signal from the exhaust
oxygen sensor to control the Bosch K-Jetronic continuous-type fuel
injection system. No EGR or air pump is used on the system.
A detailed Test Vehicle Description table, a catalyst performance
curve, and a schematic of the emission control system are included
in the following pages of this report.
Test Procedure
Exhaust emission tests were conducted according to the 1975 Federal
Test Procedure ('75 FTP), described in the Federal Register of
November 15, 1972. Additional tests included the EPA Highway Cycle
for determining highway emissions and fuel economy and a series of
tests to determine particulate and sulfate emissions. These latter
tests ('75 FTP's, '72 FTP's (hot start}, Highway Cycles, and 60 mph
steady state tests) were performed on an electric dynamometer which
can be set to the same inertia weight and horsepower loading as on the
standard Clayton dynamometer. In these tests the vehicle exhaust passes
through a tunnel 18 feet (5.5 m) long and 1.5 feet (.46 m) in diameter
before entering the constant volume sampler (CVS). A sample is
collected on a filter for each test in this series and is later
analyzed for total mass of particulates and then for sulfates using
an automated barium chloranilate method.
All tests were conducted using an inertia weight of 3500 pounds
(1589 kg) and road load setting of 12.33 horsepower (9.20 kW) at 50
miles per hour (80.5 km/hr.). This inertia weight is 500 pounds higher
than is currently used for this model vehicle, but Volvo chose the 3500
pound setting not knowing at the time of these tests the exact weight
of the vehicle for which this engine - emission control package is intended.
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TEST VEHICLE DESCRIPTION
Chassis model year/make - 1975 Volvo 242 DL
Emission control system - 3-way catalyst
Engine
model B21F
type 4-stroke Otto cycle, OHC, 1-4
bore x stroke not available (NA)
displacement 130 inches3/2130cc
compression ratio 8.5:1
maximum power @ rpm NA
fuel metering Bosch continuous flow fuel injection
fuel requirement 91 RON unleaded f
Drive Train
transmission type 3-speed automatic
final drive ratio 4.1:1
Chassis
body type model 242, 2 door sedan
tire size 175 SR 14
curb weight 2950 lbs/1344 kg
inertia weight 3500 lbs/1589 kg
passenger capacity 5
Emission Control System
basic type Lambda-sond system and 3-way catalyst
3-way catalyst type Engelhard TWC-1, TWC-9
substrate NA
volume. . . NA
loading NA
EGR type None
Air injection None
durability accumulated on system . 4,000 miles each catalyst
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The vehicle was delivered with a first generation Engelhard 3-way
catalyst, model TWC-1, installed. Emissions and particulates testing
were performed with this catalyst. A "dummy" catalyst was then installed
so that the effectiveness of TWC-1 could be determined. After this, a
current model catalyst, model TWC-9, the type planned for production
was installed. Four thousand miles of operation had been accumulated
on this catalyst, on another vehicle, prior to shipment to the EPA
laboratory. Emissions tests were performed with this catalyst at two
conditions of feedback sensor control. The sensor potentiometer had
been set at .401 volts and was changed to .500 volts upon request from
Engelhard personnel. The purpose of this was to provide a slightly
richer mixture which was felt necessary for better operation of the
catalyst; No particulate or sulfate emissions tests were performed
with TWC-9 installed.
Test Results
Exhaust emissions data, Highway Cycle fuel economy, and particulates
and sulfates results are summarized below. The Volvo prototype vehicle
met the levels required by the 1977 Federal emissions standards with
both catalysts TWC-1 and TWC-9, both at 4000 miles of durability.
Compared to the 1975 Volvos, the Volvo prototype, when fitted with
catalyst TWC-9, delivered 5% better fuel economy. This can be seen
by utilizing a formula for combining the two fuel economy values:
Composite MPG = .55 .45
FTP HC
where FTP = fuel economy on the FTP, and
HC = fuel economy on the Highway Cycle.
This information is included in the summary along with fuel
economy for two 1975 Volvo certification vehicles equipped with 4
cylinder engines and automatic transmissions, tested at 3500 pounds
inertia weight.
A comparison of the emissions from the Volvo when fitted with
catalyst TWC-9 (pot. setting .401 volts) with the emissions when the
dummy catalyst was installed yields: 85% lower HC emissions, 92%
lower CO emissions, and 57% lower NOx emissions.
Detailed emissions and fuel economy data are presented in the
Appendix of this report.
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Catalyst
TWC-1 Avg.
2 tests
of
Dummy catalyst -
1 test
TWC-9 Pot.
Setting at .40k
(as before) -
1 test
TWC-9 Pot.
Setting at .500 -
avg. of 2 tests
1975 Volvo 245
Wagon (2 vehicles)
1977 Federal
Emissions
Standards
Summary of '75 FTP Results and
EPA Highway Cycle Results
Mass Emissions
grams per mile
(grams per kilometre)
HC
.41
(.25)
CO
NOx
.22 N
(.14)
1.79
(1.11)
.27
(.17)
.24
(.15)
.90
(.56)
11.4
(7.07)
.93
(.58)
1.18
(.73)
1.70
(1.05)
4.60
(2.85)
1.96
(1.22)
1.44
(.89)
3.4
(2.1)
2.0
(1.2)
Fuel Economy/Fuel Consumption
miles per gallon
(litres per 100 kilometres)
Urban
Highway
.24
(.15)
1.18
(.73)
1.44
(.89)
17.8
(13.2)
16.9
(13.9)
24.0
(9.8)
23.0
(10.2)
Composite
19.3
(12.2)
18.6
(12.6)
17.9
(13.1)
26.4
(8.9)
24.6
(9.6)
23.6
(10.0)
22.0
(10.7)
20.9
(11.3)
20.1
(11.7)
20.2
(11.6)
19.2
(12.2)
Test Type
Particulate and Sulfate Emissions Results
Total Particulates Sulfuric Acid
Number of
Tests
Milligrams per mile
3.5 + 0.7
1.7 + 0.4
1.1 + 0.5
0.4 +0.2
Milligrams per mile
0.0*
0.0
0.0
0.0
Converted
to Sulfate
0.0
0.0
0.0
0.0
'75 FTP 4
'72 FTP (Hot Start) 4
Highway Cycle 8
60 MPH 16 _
Steady Sate
X
* Below detectability. This means the sulfuric acid content was less than
.1 mg per mile. Cars without catalysts often show about 3 mg per mile.
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Conclusions
At low mileage, using either catalyst TWC-1 or TWC-9, the Volvo
prototype vehicle met the 1977 Federal emissions standards with a
small improvement in fuel economy over 1975 model Volvos. Durability
testing of the system will have to be performed to determine if the
system has the capability of meeting the standards at 50,000 miles, which
is necessary for certification of a vehicle. Although the catalyst
has shown high conversion efficiencies after 1000 hours of bench
testing, further testing of the system in a vehicle is necessary to
establish durability, since vehicle durability of 3-way catalyst
systems historically has been a problem.
The Volvo with the TWC-1 catalyst installed emitted very low
levels of both particulate and sulfate (reported as sulfuric acid
mist) emissions. Both levels were the lowest obtained at this
laboratory on any system tested thus far.
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Table I
1975 FTP Composite Results
Mass Emissions, grams per mile
Fuel Economy, miles per gallon
Catalyst
TWC-1
Dummy
Catalyst
TWC-9, .401V
setting
TWC-9, .500V
setting
Catalyst
TWC-1
TWC-1
TWC-1
TWC-1
Dummy
Catalyst
Test No.
19-6663
19-6701
19-6735 1
16-7064
16-7091
15-7100
Manufacturer
HC
.22
.23
.79
.27
.23
.26
's
Odometer
Mileage HC
0
4090
4134
4145
4157 1.
4168 1.
18
30
23
27
53
56
CO
o74
1.06
11.4
.93
1.38
.98
Supplied Data
CO
1.24
1.53
1.31
1.10
12.1
10.8
NOx
1.73
1.67
4.60
1.96
1.46
1.41
NOx
.25
1.03
1.12
.90
5.10
4.89
Fuel Economy
19.3
19.3
18.6
17.9
18,2
17.4
Fuel Economy
17.0
17.7
17.9
18.5
18.2
18.8
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Table II
1975 FTP Individual Bag Results
Mass Emissions, grams per mile
Fuel Economy, miles per gallon
Test No.
19-6663
19-6701
19-6735
16-7064
16-7091
15-7100
HC
.61
.57
2.05
.70
.55
.69
Bag 1
CO
" 2.95
3.89
14.60
3.12
4.23
3.39
Cold Transient
C02
495.0
481.0
479.4
519.5
500.4
521.4
NOx
2.30
2.43
6.37
2.81
2.30
2.08
Fuel
Economy
17,7
18.1
17.4
16.8
17.4
16.8
HC
.11
.11
1.68
.13
.14
.12
Bag 2 Hot Stabilized
CO
.18
.37
10.75
.45
.89
.47
C02
466.7
461.1
456.1
495.3
490.0
519.7
NOx
1.38
1.14
3.13
1.19
.90
.94
Fuel
Economy
19.0
19.2
18.6
17.9
18.0
17.0
HC
.14
.19
1.81
.18
.15
.20
Bag Hot Transient
CO
.13
.23
10.27
.17
.15
.16
C02
413.2
429.6
429.6
434.3
461.5
476.3
NOx
1.98
2.13
6.08
2.55
1.88
1.82
Fuel
Economy
21.4
20o3
19.7
20.4
19.2
18.6
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11
Table III
EPA Highway Cycle
Emissions Results and Fuel Economy
Mass emissions, grams per mile
Fuel Economy, miles per gallon
Catalyst
TWC-1
Dummy
Catalyst
Test No.
19-6618
19-6701
19-6735
HC
.07
.06
.56
CO
.07
.05
4.74
NOx
.75
.88
5.04
Fuel Ec<
25.6
26.4
24.6
TWC-9, <>401
pot setting 16-7064
TWC-9
.500 V
16-7091
15-7100
.06
.14
.11
.03
.23
.16
1.83
.27
.23
23.6
23.5
24.5
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11
Table III
EPA Highway Cycle
Emissions Results and Fuel Economy
Mass emissions, grams per mile
Fuel Economy, miles per gallon
Catalyst
TWC-1
Dummy
Catalyst
Test No.
19-6618
19-6701
19-6735
HC
.07
.06
.56
CO
.07
.05
4.74
NOx
.75
.88
5.04
Fuel Ec<
25.6
26.4
24.6
TWC-9, .401
pot setting 16-7064
TWC-9
.500 V
16-7091
15-7100
.06
.14
.11
.03
.23
.16
1.83
.27
.23
23.6
23.5
24.5
Table IV
'75 FTP Composite Results from
Electric Dynamometer During Sulfate Test Program
With Catalyst TWC-1
Mass Emissions, grams per mile
Fuel Economy, miles per gallon
Test No.
16-6805
16-6808
16-6822
HC
.26
.28
.22
CO
1.68
1.31
1.26
NOx
2.50
2.60
2.27
Fuel Economy
18.2
18.7
18.5
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12
Table V
'72 Hot Start LA-4 Composite Results
from Electric Dynamometer During Sulfate
Test Program with Catalyst TWC-1
Mass Emissions, grams per mile
Fuel Economy, miles per gallon
Test No.
16-6793
16-6806
16-6809
16-6823
HC
.14
.14
.16
.14
CO
.30
.35
.32
.51
Table VI
NOx Fuel
2.24
2.44
2.49
2.42
Economy
19.3
18.8
19.3
19.0
Highway Cycle Results from Electric
Dynamometer During Sulfate Test Program
with Catalyst TWC-1
Mass Emissions, grams per mile
Fuel Economy, miles per gallon
Test No.
16-6792
16-6793
16-6805
16-6806
16-6808
16-6809
16-6822
HC
.08
.12
.14
.09
.13
.09
.13
CO
.04
.16
.24
.04
.14
.05
.18
NOx Fuel
2.53
2.69
3.08
2.89
3.17
3.21
2.98
Economy
24.. 4
24.5
23.4
23.5
23.3
22.5
24.0
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13
Test No.
16-6807
16-6807
16-6810
16-6810
16-6824
16-6824
Table VII
60 mph Steady State Results from
Electric Dynamometer During Sulfate Test
Program with Catalyst TWC-1
Mass Emissions, grams per mile
Fuel Economy, miles per gallon
HC
.06
.07
.07
.07
.07
.07
CO
.02
.02
.02
.02
.01
.01
NOx
2.47
2.75
2.93
3.11
3.27
3.01
Fuel Economy
25.2
23.3
23.8
22.8
23.4
23.6
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