EPA-AA-TAEB 76-22
Exhaust Emissions from an Opel Diesel
Equipped with Reverse Flow Damping Valves
June 1976
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Environmental Protection Agency
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Background
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 Emission Laboratory at
Ann Arbor, Michigan. The results of all such test projects are set
forth in a series of Technology Assessment arid 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 vehicles 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 the EPA evaluation test can be considered to
be quantitatively valid only for the specific test vehicle 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.
As part of an ongoing program to evaluate the exhaust emissions and
fuel economy of light-duty Diesel-powered vehicles, the EPA agreed to
test an Opel Rekord 2100D supplied by Ford Motor Company. The purpose
of the test program would be to evaluate a reverse flow damping valve
designed by Bosch for installation in the injector lines. The damper
valve is designed to eliminate undesirable erratic injection into the
combustion chamber due to stray pressure pulses in the injection lines.
Test Vehicle Description
The test vehicle is an Opel Rekord 2100D, powered by a 2100cc
Diesel engine, and equipped with a four-speed manual transmission. The
inertia class is 3000 Ibs. A tabulation of pertinent vehicle statistics
is given in the Vehicle Description on page 7.
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Stray pressure pulses normally exist in the injection lines following
injection of fuel into the combustion chamber. These pulses can cause
the injector to "dribble" small amounts of fuel into the combustion
chamber. By installing valves in the injection lines to dampen the
stray pressure pulses, the dribbling of the injector is reduced or
eliminated and a small decrease in emissions of unburned hydrocarbons
may occur. The reverse flow damper valve is placed in the injection
system between the injection line and fuel pump. One valve is used in
each injection line.
Test Program
The test program was conducted in accordance with the 1975 Federal
Test Procedure ('75 FTP) for light-duty Diesel vehicles (Federal Register,
October 22, 1974, Vol. 39 No. 205, Part III). Testing included measure-
ment of exhaust emissions and fuel economy according to the '75 FTP and
the EPA Highway Fuel Economy Test (HFET).
The vehicle was tested in two configurations. The first configura-
tion, the baseline, involved no changes to the manufacturer's production
injection system. The second configuration was with the damper valves
installed in the injection lines.
In both configurations the vehicle was tested twice according to
the '75 FTP and once according to the HFET.
Test Results
Exhaust emissions and fuel economy measured during the "75 FTP are
presented in the following table:
'75 FTP mass emissions in
grams per mile
(grams per kilometer)
Fuel Economy
HC CO NOx (Fuel Consumption)
0.41 1.5 1.21 27.6 miles/gal.
(0.26) (0.9) (0.75) (8.5 liters/lOOkm)
0.38 1.5 1.18 27.9 miles/gal.
(0.24) (0.9) (0.74) (8.4 liters/lOOkm)
-7% 0 -2% +1%
(-1%)
Baseline-avg.
of 2 tests
Damper valves
avg. of 2 tests
% Change
from baseline
A further breakdown of '75 FTP emissions and fuel economy is given in
Tables I and II. Highway Cycle emissions and fuel economy are presented
in Table III.
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At the low exhaust emission levels measured from the test vehicle,
it is difficult to attach importance to percent changes in emissions.
For instance, the 7% reduction in HC emissions during the '75 FTP
corresponds to a change in mass emissions of only 0.03 gram per mile.
Based on an average of only two tests, a change of this magnitude cannot
be accurately quantified. The 7% change in HC emissions can be taken to
be representative of a trend toward lower HC emissions with the damper
valves installed.
Conclusions
1. Installation of the damper valves resulted in a small decrease
in unburned hydrocarbon emissions. Further testing is required to
more accurately quantify this reduction.
2. No significant effect on fuel economy occurred during the '75
FTP and Highway Fuel Economy test.
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Table I
'75 FTP mass emissions in
grams per mile
(grams per kilometer)
Test #
Baseline
77-1634
77-1635
Average
Damper Valves
77-1677
77-1678
Average
% change
from baseline
HC
0.43
(0.27)
0.39
(0.24)
0.41
(0.26)
Installed
0.37
(0.23)
0.38
(0.24)
0.38
(0.24)
-7%
CO
1.5
(0.9)
1.5
(0.9)
1.5
(0.9)
1.5
(0.9)
1.4
(0.9)
1.5
(0.9)
0
CO 2
361.
(224.)
371.
(230.)
366.
(228.)
356.
(221.)
369.
(229.)
363.
(225.)
-1%
NOx
1.19
(0.74)
1.22
(0.76)
1.21
(0.75)
1.17
(0.73)
1.19
(0.74)
1.18
(0.74)
-2%
miles/gal.
28.0
(8.4)
27.2
(8.6)
27.6
(8.5)
28.3
(8.3)
27.4
(8.6)
27.9
(8.4)
+1%
(-1%)
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Table II
Individual Bag Emissions in grams per mile
Bag 1: Cold Transient
Test #
Baseline
77-1634
77-1635
Average
Damper Valves
77-1677
77-1678
Average
% change
from base-
line
HC :
0.44
0.43
0.44
0.40
0.43
0.42
-5%
CO
1.6
1.6
1.6
1.5
1.5
1.5
-6%
CO
39.1.
402.
397.
394.
399.
397.
0
NOX
1.20
1.25
1.23
1.18
1.20
1.19
-3%
MPG
25.8
25.1
25.5
25.6
25.3
25.5
0
Bag 2: Stabilized
HC CO CO NOx MPG
0.45
0.41
0.43
0.38
0.40
0.39
1.5
1.6 .
.1.6
1.7
1.5
1.6
360.
368.
364.
351.
367.
359.
1.22
1.25
1.24
1.21
1.23
1.22
28.0
27.4
27.7
28.8
27.5
28.2
-10% 0
-1%
-2%
+2%
Bag 3:
HC
0.35
0.33
0.34
0.32
0.32
0.32
CO
1.2
1.2
1.2
1.3
1.2
1.3
Hot Transient
CO
340.
352.
346.
337.
350.
344.
NOx
1.11
1.15
1.13
1.07
1.10
1.09
MPG
29.7
28.7
29.2
29.9
28.9
29.4
+8% -1%
-4%
+1%
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Table III
Test #
Baseline
77-1639
HC
0.22
(0.14)
HFET mass emissions in
grams per mile
(grams per kilometer)
CO
0.9
(0.6)
C02
276.
(172.)
NOx
0.97
(0.60)
miles/gal. (liters/lOOkm)
36.6
(6.4)
Damper Valves installed
77-1679
0.25
(0.16)
0.9
(0.6)
271.
(168.)
0.90
(0.56)
37.3
(6.3)
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TEST VEHICLE DESCRIPTION
Chassis model year/make - Opel Rekord 2100D
Emission Control system - None
Engine
type 4 stroke, Diesel, 1-4, ohv, indirect injection
bore x stroke . . . 3.47 x 3.34 in./88.2 x 84.8 mm
displacement 126 cu in./2070 cc
compression ratio 22:1
maximum power @ rpm 68 bhp/50.7 kW @ 4300 rpm
fuel metering Bosch fuel injection
fuel requirement #2 Diesel
Drive Train
transmission type 4 speed manual
Chassis
type front engine, rear wheel drive
tire size 165 x 14
inertia weight 3000 Ib.
passenger capacity 5
Emission Control System
basic type None
durability accumulated on system . . 3400 mi/5400 km
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