TTT T ] i |
8 t r
a Hi 7
i
t
[ Li
i j
i
Goo t t + =
4 i i
H i
{
[G@mfni | i
4400 t ;
ti H {
i j i
oe a
=a
mam T
200 +—+—$ i
H i
t
i i ! :
| | Ly
ai i ot i
° Pep |
Baa #1 BAG 42 Bagi BAG a2
coLD couD HoT HoT

Figure 17 - Mean and Standard Deviation of co,
g 54 Fleet Cars
{ Jeep with FCP Engine (EPA)


-Start Bag 2

eo
i)
oe
eo
Fa
ge
o%
2
Sa
3
g§
ie}
3
a U
av
a<
A
N
oo
Z>
v
i=}
g
o
w
3
“
&
a
OD
a
i)
» oO
aa
a8
|
3.
33
oD
g§
i}
3
oO
oY
gs
3
ag
eo
>

Figure 9 - NO


similaz although the HC, CO, ard NOL valves of the FCP engire ere
strikingly lower than those of the 54 cars (due to effective emission control

and lack of variance between engines),

Table 2

Constant Volume Sampler Results of FCP Engine
EPA, October 7, 1971 (Reference 2}

T Standard Rel,
Bag Size | Gas Mean Deviation Variation

gr/mi gr/mi %

HC - FID 0.97 0.16 16

Cold 4 co -IR 1,30 0. 43 33
Start CO, -IR 480, 45. 9
“NO, - CI 0, 40 0.13 33

HC - FID 0.18 0.05 3

cO-IR 0.78 0.28 36

Stabilized | 14 CO, -1R 509. 37. 7
NO, - cl 0, 28 0. 06 22

HC - FID 0.27 0. 03 11

Hot 4 co-IR 0, 76 0, 26 34
Start CO2 - IR 451, 53, 12
NO,, - CI 0. 39 0.12 30



LT

—— T
t2o -
— facet fae [ ul H is
i T
|
&o
ot q
r
cr
40 ii +
m4 rt
pt tt +
i 1
| Hl q ;
fi.
| +
° i i i { } = i
BAG #I Bacal BAG #2
cord HoT HoT

Figure 15 - Mean and Standard Deviation of CO
¢ 54 Fleet Care

| Jeep with FCP Engine (EPA)
(10 times enlarged)


leage

i

{ Cold-Start Bag 2

‘igure 2 - CO Emissions o
Versus Accumulated M:

FE

-Start Bag 1

ions of Cold
Versus Accumulated Mileage

re 1 - CO Emiss

Fi


Yut = mass emissions of pollutant (CO, HC, NO,) as calculated
from the hot-transient phase (bag) of the hot-start test, in

grams

Y_ = mass emissions of pollutant in gr/mi, CVS-C test procedure

Y = weighted mass emissions of pollutant in gr/mi; CVS-CH

procedure

These computations were performed for each of the 54 cars (actually only
53 because one car's data were quite erratic and had to be omitted), For
each car, the ratio of Ym! m was then calculated, and the mean and the
standard deviation of the distribution of these ratios computed, The results

are listed in Table 3 together with the standard deviation of the mean

(s an* s/ 53).

me

Table 3
Comparison of Emission Levels Computed
According to CVS-C and CVS-CH Method

Y = CVS-CH Mass Emissions in gr/mi
wm

Yi, 7 CGVS-C Mass Emissions in gr/mi
Pollutant Ym! Yon Yom! Yon Number Standard
Mean Standard of Deviation
© Deviation Cars of Mean
HC 0. 88 0, 07 53 0.01
co 0.71 0.13 53 0,02
NO, 1,01 0.05 53 0.01

Table 3 demonstrates clearly the attenuating effect of bag weighting as
regards to HC andCO, The HC level is reduced by 12% and the CO level by
even 29%, The NO, level, on the other hand, remains unaffected.

6


CVS-C VERSUS CVS-CH TEST PROCEDURE

The Constant Volume Sampling Procedure for 1972 prescribes a 1369
second, 7.5 mile, non-repetitive driving cycle with a 12-hour cold soak

before testing and a cold start (Notation: CVS-C).

The Constant Volume Sampling Technique for 1975-76 prescribes the
same 7,5 mile driving pattern as the 1972 procedure, The emissions of the
first 505 seconds are collected in a ''cold transient" bag, those of the next
864 seconds ina ''stabilized"' bag. After ten minutes hot soak with engine
off, the 7.5 mile driving cycle is repeated with the emissions of the first
505 seconds collected in a "hot transient" bag (Notation: CVS-CH). The
first cold bag is weighted by a factor of 0.43, the second transient bag by
a factor of 1, and the third hot bag by 0,57, All weighted emissions are

then added and the sum divided by 7.5 to give the emissions in gr/mi.

In order to compare the CVS-C and the CVS-CH procedures, the four-
bag data of the 54 cars (a cold-transient bag, a cold stabilized bag, a hot-

transient bag, and a hot-stabilized bag) were assembled in two ways.

CVS-C (Y¥ + ¥__)/7.5 = Y in gr/mi
et cs m
- a Y A . = i i
CVS-CH (0. 43 Yet + cs + 0.57 ¥y/7 5 Y om in gr/mi
Yet = mass emissions of pollutant (CO, HC, NO,) as calculated
from the cold-transient phase (bag) of the cold-start test,
in grams
Yos = mass emissions of pollutant (CO, HC, NO.) as calculated

from the cold-stabilized phase (bag) of the cold-start test,

in grams


8T

1

r ra
i io: : i
i TT i : j
jo i {i i
| Hl rt F i
i i i H 7 i i
+ —— T t ; :
a +
4 je. ef
+ c { %
[ I i
i | 4
Jha
if a |
es i
_ {
rt
i |
roid i
i i
+ E :
iE H i
je
H i. :
{
| {
| |
| i
i | [4 i
BAG #1 BAG #2 BAG“! BAG 2
CoLD coud HoT Hor

Figure 16 - Mean and Standard Deviation of NO,
% 54 Fleet Cars
| Jeep with FCP Engine (EPA)


REFERENCES
1. Cornell Aeronautical Laboratory, Inc.: "Analysis of Aircraft
Exhaust Emission Measurements" - CAL No, NA-5007-K,

November 1971,

2. Private Communication: Computer Printout of EPA,


CORNELL AERONAUTICAL LABORATORY, INC,
Vehicle Research Department
Buffalo, New York 1422]

EMISSIONS ANALYSIS OF 54 FLEET-TYPE
PASSENGER VEHICLES

January 1972

Prepared for

Environmental Protection Agency
Division of Advanced Automotive
Power Systems Development

Ann Arbor, Michigan 48105


ll

-Start Bag 2

ions of Cold
Versus Accumulated Mileage

iss

- HC Em

Figure 6

HC Emissions of Cold-Start Bag 1
Versus Accumulated Mileage

Figure 5 -


ia Sand EAE

10

Start Bag 2

ssions of Hot
Versus Accumulated Mileage

i

4 -CO Em:

igure

F

f Hot-Start Bag 1
Mileage

iss.

CO Emissions a!
Versus Accumulated

igure 3 -

F


SUMMARY

Fifty-four fleet cars of different makes and mileages, all 1970 models,
were tested by EPA using both the CVS cold-start and the CVS hot-start test
conditions, Although the accumulated mileage of the cars tested ranged from
approximately 4, 000 to 35,000 miles, a correlation between mileage and level
of CO, HC, NO, emissions was not detectable. (There was a slight but

significant increase of CO, with mileage, however.) The mean and the

standard deviations of the co and HC emissions sampled in the cold-start

bag were significantly higher than those of subsequent bags. The HC mean

of the cold-start bag was approximately 1.6 times higher; the CO mean,

3.4 times. Also, the standard deviation of both emissions seemed to change
approximately proportional with the mean, The situation was different for

NO... Here, the mean of the first bag was always higher than that of the
subsequent bag regardless of starting conditions. The co, level remained
approximately constant for all bags. The results were qualitatively corroborated
{except for mileage effects) by results of emission tests performed by EPA

on one FCP engine installed in a jeep.

An investigation of the effect of bag weighting on the measured emission
level revealed that the CVS-CH technique produces a 12% lower HC level
than the CVS-C procedure and a 29% lower CO level. The NO, level remains
unaffected.


INFLUENCE OF START CONDITIONS ON EMISSIONS LEVEL

Figures 14 through 17 depict the means and the standard deviations of
the HC, CO, NO,, and CO2 constituents for each of the four bags. The mean
is indicated by a small circle, the standard deviation by the length of the
vertical bar extending from the mean value in both directions, Obviously,
the HC and the CO contents (in gr/mi) of the first (cold-transient) bag are
significantly higher than those of the rest, In fact, the differences between
the second (cold-stabilized), third (hot-transient), and fourth (hot-stabilized)
bag are so slight as to suggest a constant level of CO and HC emissions after
the first bag. Thus, the HC level of the first bag is approximately 1, 6 times
higher than the average level of subsequent bags, and the CO level of the
first bag approximately 3.4 times higher, The situation is different for NO,.
Here, the NO, content of the first bag is always higher than that of the
subsequent bag regardless of whether the engine is started after a cold soak
ora hot soak, The CO? level is of lesser importance, We note that it

remains approximately unchanged,

Another descriptor of interest is the standard deviation. In HC and
CO emissions, the standard deviation seems to change proportionally with
the mean, an observation confirmed by analyses of aircraft emission data
(Reference 1), The standard deviations of both NO, and co,, however,

indicate no dependence on the mean,

For comparison, the emission data of the 54 cars were contrasted
with the emission data of an FCP engine installed in a jeep (Reference 2),
The FCP data are listed in Table 2 and indicated in Figures 14 through 17
by black bars; the bar center is identical with the mean, the bar length

with twice the standard deviation, The general trends of both plots are


-Start Bag 2

f Hot

2 Emissions o:
Versus Accumulated Mileage

NO

Eigure 12 -

it)
LJ
Oy
yp wD
88
ant
Ova
£2
x3
g
Sa
3
g§
°
8
23
ae
a
N
O°
Z>

Figure 11 -


9t

i
{
i
i L
+t
im
# +—
io
te +—t
L- | a | ut
BAG #t BAG #2 BAG #/ BAG #2
coup CoLD HoT HoT

Figure 14 - Mean and Standard Deviation of HC

t 54 Fleet Cars
(| Jeep with FCP Engine (EPA)



INFLUENCE OF ACCUMULATED MILEAGE ON EMISSIONS LEVEL

The accumulated mileage of the cars tested ranged from approximately
4,000 miles to 35,000 miles. A visual inspection of the emissions data
from an analysis of-each bag plotted versus accumulated mileage strongly
suggested negligible correlation between the two variables, Figures 1
through 12, An analysis of variance, described elsewhere, also failed to
reveal a mileage trend (nor did it confirm any other trend associated with
number of cylinders, displacement, and car weight), Hence, all cars can

be considered as drawn from the same homogeneous population,

As an interesting aside, it may be mentioned that in contrast to the
toxic emission components (CO, HC, and NOx), the non-toxic component
of CO2 did indeed reveal a mileage correlation, Figure 13 shows CO2
data in gr/mi for the first cold bag as a function of mileage suggesting an
upward trend of emissions with mileage. An analysis of variance, Table 1,
confirmed the significant contribution of mileage to the overall variability

of CO2,

Table 1

Analysis of Variance on CO, Emissions (gr/mi) of Fifty-
four Cars, Divided into Three Mileage Classes (<10, 000;
10,000 - 20,000; > 20, 000 miles)

Degree of
Source Sum of Squares Freedom Mean Square
. 4 4
Between mileage classes} 14,92 x10 2 7.69 x 10
Within mileage classes 65. 80 x 104 51 1.29 x 10*
TOTAL 81.72 x 104 53 IF = 6,17 ;
25.0
F'2, 51, 99%



INTRODUCTION

Fifty-four 1970-model fleet cars of different makes and mileages
were tested by EPA using both the CVS cold-start and the CVS hot-start
test conditions. On November 15, 1971, CAL received from EPA the results
of these emission tests with the following remarks: ''A two-bag cold start
test was run on each car followed by a two-bag hot start test. To obtain
three-bag data, it is necessary to weight and assemble the data from the
two cold start bags with the first bag of the hot start test using the procedure
described in the Federal Register. '' The identity of the vehicles could not
be disclosed by EPA in any way other than by range of engine displacement,

number of cylinders, accumulated mileage, and car weight.

The emission data listed in the computer print-outs gave occasion to

study the following questions:

e To what extent does the accumulated mileage influence the

emissions level?

e Is there a significant difference between the emissions levels

for cold start and hot start?

° What is the numerical relation between the CVS-C and the

CVS-CH testing procedure?

The answers to these questions were felt to provide, by inference, some

inputs into the planning of Stratified-Charge-Engine tests.


-Start Bag 2

o
oD
8
o
3
a
bs
2
ov
og
a
2 §
398
a YU
a4
Bio
u
Oo
i>
t
oO
oO
M4
3
&
fy
4
Oo
S
2
Ho
Sa
as
mA
asl
co}
od
a
2§
a
9
ot
a
a
3
Q
H
o
>

HC Em:

Figure 7 -


ST

2,000

1, 000

B00

soo

30a

Zoo

ao

Figure 13 - co, Emissions of Cold-Start Bag 1 Versus Accumulated Mileage