72-8
EVALUATION OF THE EMISSION REDUCTION
WITH THE PERFECT CIRCLE RETRONOX
SPEED CONTROLLED EGR SYSTEM
October 1971
Henry L. Gompf
Mobile Source Pollution Control Program
Office of Air Programs
Environmental Protection Agency
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Background
Preliminary evaluations indicated that the Perfect Circle
Retronox device caused substantial reduction in total oxides
of nitrogen emissions from passenger vehicles. While the
device is still in the development stage it appears that it
has potential usefulness as a used-car retrofit device
as well as potential for new vehicle applications.
Device
Basically the Retronox device is a speed controlled EGR and
distributor vacuum advance cut-off system, both effective
procedures for reduction of total oxides of nitrogen. Exhaust
gas is picked up from the exhaust pipe under the car. An
EGR valve is actuated by an engine vacuum controlled solenoid
valve which in turn is controlled by a—spe'ed-sensing switch
driven by the speedometer cable. When open, the EGR valve
allows exhaust gas to flow into the intake manifold by means
of a base plate installed under the carburetor. The speed
sensing switch is also used to actuate a solenoid valve
restoring distributor vacuum advance. This solenoid valve
can be the same one as for the EGR system if it is desireable
to restore vacuum advance and introduce exhaust gas recirculation
at the same speed. Figure I and Figure II indicate the con-
figurations, double and single solenoid, used for the 1971
Chevrolet. Figure III, A and B, indicates the similar con-
figuration employed on the 1964 Plymouth. The system installed
on the 1963 Chevrolet is similar to that employed in Figure IIIA.
It should be noted that in the single solenoid valve applications
a micro-switch is used to shut off EGR and cut-off vacuum advance
during closed throttle operations.
Test Program
Three vehicles were employed to evaluate the effectiveness of
the Perfect Circle Retronox device. The first car tested was
a 1971 Chevrolet Impala equipped with a 400 CID engine, auto-
matic transmission and a two-barrel carburetor. This vehicle
was tested in both the single and double solenoid valve con-
figuration. A single solenoid valve system was installed on
a 1963 Chevrolet Impala with a-283'CID engine, manual three-
speed transmission, and two-barrel carburetor* Finally a 1964
Plymouth Fury with a 318 .CID engine, automatic transmission,and
two-barrel carburetor was tested employing both the single and
double solenoid valve systems.
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The vehicles were tested both in baseline and device equipped
configurations by the 1972 Federal emission test procedure as
described in the November 10, 1970 Federal Register. The bag
s.amples obtained by this constant volume sampling procedure
were analyzed by FID analysis for hydrocarbons, NDIR analysis
for CO and C02, and chemiluminescence analysis for oxides of
nitrogen.
Results
Tables I, II, and III in the Appendix indicate the test results
for the 1971 Chevrolet, 1963 Chevrolet, and 1964 Plymouth
respectively. The following percent reductions over baseline
were measured:
1971 Chevrolet
1 solenoid valve
2 solenoid valves
1965 Chevrolet
1 solenoid valve
1964 Plymouth
1 solenoid valve
2 solenoid valves
HC_
19%
14%
32%
10%
13%
CO
10%
19%
57%
6%
11%
C0_2
NOx
7% inc. 31%
16% inc. 46%
68%
23% inc. 65%
17% inc. 70%
It should be noted that the baseline emissions for the 1963
Chevrolet were made without the carburetor base plate in
position. The added fuel-air mixing caused by this plate
may account for the significant reduction in carbon monoxide.
The Plymouth was operating quite rich (10% carbon monoxide
at idle) indicating that certain cylinders may have experienced
occasional misfire due to rich limit combustion. This may
account for the increase in hydrocarbon emissions measured
during the evaluation.
Conclusions
The Retronox system demonstrates significant effectiveness in
reducing oxides of nitrogen. In general these emissions can
be reduced by over 50%. There also appears to be a smaller yet
consistent reduction in hydrocarbon and carbon monoxide possibly
resulting from increased fuel-air mixing hence more homogeneous
delivery to the individual cylinders. It is anticipated that
installation of the system will result in decreased fuel
economy. This observation is supported by the increases seen
in carbon dioxide emissions during the evaluations.
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Little adverse effect on .driveability was noted or anticipated
as the system does not initiate EGR during the most sensitive
engine operating modes; e.g. low vehicle speed power operations.
The cost of the system will be a crucial parameter in the con-
sideration of Retronox as a retrofit device. Since the system
is still in the development stage little idea as to the installed
cost to the individual consumer is available.
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SPEEDOMETER
SOLENOID
INTAKE MANIFOLD
• w • L» • o «
SWITCH
33 MPH
EXHAUST PTPE
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SPEEDOMETER
O • o • O •
SWITCH
23 MPH
INTAKE MANIFOLD
s.c.s.
SWITCH
33 MPH
EXHAUST PITE
-rr
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,,,,/;u 1964 PLYMOUTH FURY - 318 C.I.D. V-8 ENG.
2V Stromb., 9:1 Comp. R.> Automatic Transm.,-Gross Wt. 3700 .Ibs
SPEEDOMETER
A
SW.
OP&NS*
CLO&&S1 M.P.H.
FLU 6
'*•• • W i*^ "^^ "'_^*
±, \P o/
.. HOSE. 5/32. \.D. . CARS-
' ""'I.~WCV SOURCE. FOOT \S
p-c
RETRO MO X
.TO
B
TRAUSW.
15-5 M. P.H.
CLOSES *5-5 M.P.H.
CONTROLS SPARK
O?EKS 4-1 NA. P. H.
CUOStS Z.1 M.P. rt-
P.O.- DANA
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Table I
1971 Chevrolet Impala Emissions
(grams per mile)
1972 FTP
Baseline HC
4.0
3;3
Average 3.7
Retronox (one switch system)
3.0 57.7 779.9 2.4
% Reduction
over baseline 19% 10% 7% 2.4
Retronox (two switch system)
3.2 51.9 845.7 1.9
% Reduction
over baseline 14% 19% 16% inc. 46%
CO
63.4
65.1
64.3
C02
701.9
753.9
727.9
NOx
3.4
3.5
3.5
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Table II
1963 Chevrolet Impala Emissions
(grams per mile)
1972 FTP
Baseline H£
8.3
Retronox (one switch system)
4.7
6.5
Average 5.6
% Reduction
over baseline 32% 571 0% 68%
C£
113.8
47.5 •
50.6
43. 1
C02
404.5
401.9
401.9
NOx
1.4
.34.
.56
.45
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Table III
1964 Plymouth' Fury Emissions
(grams per mile)
1972 FTP
HC
7.5
CjO
116,. 4
CC>2
418.1
NOx
3.7
Baseline
Retronox (one switch system; common EGR inlet and vacuum source)
6.8 109.9 513.6 1.3
% Reduction
over baseline 10% 6% 23% inc. 65%
Retronox (two switch system; common EGR inlet and vacuum source)
8.5 103.4 491.5 1.1
% Reduction
over baseline -13% 11% 17% inc. 70%
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