EPA/AA/CTAB/PA/80-5
TECHNICAL REPORT
Comparison of Gas Phase Hydrocarbon Emissions From
Light-Duty Gasoline Vehicles and Light-Duty Vehicles
Equipped with Diesel Engines
by
Penny Carey
Janet Cohen
September, 1980
NOTICE
Technical reports do not necessarily represent final EPA decisions or
positions. They are intended to present technical analyses of issues
using data which are currently available. The purpose in the release
of such reports is to facilitate the exchange of technical information
and to inform the public of technical developments which may form the
basis for a final EPA decision, position or regulatory action.
Control Technology Assessment and Characterization Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air, Noise and Radiation
U.S. Environmental Protection Agency
2565 Plymouth Road
Ann Arbor, Michigan 48105
-------
Comparison of Gas Phase Hydrocarbon Emissions from Light-Duty Gasoline
Vehicles and Light-Duty Vehicles Equipped with Diesel Engines '";
I. Introduction
The composition of the hydrocarbons in automobile exhaust is profoundly
influenced by many factors, including emission control systems. The use
of catalytic converter control systems, for example, has brought about a
significant change in the detailed patterns of the hydrocarbon emissions
from gasoline vehicles. The composition of the hydrocarbon mixture in
gasoline catalyst and non-catalyst automobile exhaust gases has been
extensively studied and individual hydrocarbon data is available. This
type of detailed information is not available for Diesel emissions at
this time because Diesel emissions contain hydrocarbons of higher molecu-
lar weight than gasoline emissions. The gas chromatograph systems used to
date do not have adequate resolution to permit identification of many of
these higher molecular weight hydrocarbons; therefore, the available
hydrocarbon data for Diesel equipped vehicles is mostly in terms of
carbon number. Currently, particle-bound organic emissions from vehicles
equipped with Diesel engines are being studied; however, not only parti-
clebound organics are emitted in Diesel exhaust. A significant fraction
of the total organics are emitted in the gas phase.
Hydrocarbons are regulated by the EPA because of their participation in
atmospheric photochemistry, creating ozone. Regulation of hydrocarbon
emissions, historically, has been based on potential atmospheric photo-
chemistry rather than potential carcinogenicity. Individual hydrocarbon
carcinogenic potency may be an important factor to consider in future
regulations.
Few comparisons of Diesel and gasoline gaseous hydrocarbon emissions have
been made to date. The purpose of this document is to consolidate much
of the existing data on gas phase hydrocarbon exhaust emissions from both
gasoline vehicles and vehicles equipped with Diesel engines. This subject
is of interest because new studies have shown Diesel emissions to contain
compounds of high molecular weight. This high molecular weight component
is dominated by particlebound hydrocarbons; however, the potential
health risk associated with heavy hydrocarbons merits examination of the
gas phase as well. Particular emphasis will be placed on the comparison
of emissions and their potential carcinogenicity. Other areas to be
discussed include evaporative hydrocarbon emissions and the effect of
fuel composition on gasoline gaseous hydrocarbon emissions.
II. Gasoline Vehicles
A. Tailpipe Emissions
The hydrocarbon composition of gasoline engine exhaust consists
primarily of components with carbon numbers 1 through 10. These
hydrocarbons exhibit distinct peaks on a gas chromatograph profile.
The individual compounds, therefore, can be readily identified.
Table 1 lists the individual hydrocarbons corresponding to the
-------
TABLE d.
IND1V1DUAL HVDRO'GARBONS IN GASOLINE EMGIME EXHAUST
0 - OLEFIN
P- PARAFFIN
A = AROMATIC
Peak Ho.
Compound
Class
Carbon Number
1
2
3
4
5
6
7
8
9
10
11
12
13
U
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
43
49
50
51
52
53
54
55
56
57
Methane
Ethylene
Ethane
Acetylene
Propylene; oropane
Propadisr.e
Methvl acet'/lene
Isobutane
Sutene 1; isobu'vlene
M-butane; 1 , 3-butadiene
Trans-2-butene
Cis-2-butene
. 3-methvl-l -butane
Isooentane
Pentene-1
N-oentane; 2-methyJ-l-butene
Trans-2-oentene
C1s-2-oentene
2-methvl-2-butene
Cyclooentane; 3-methyl-l-pjntene
2,3-dircethylbutane
2-methvlpentane; 2,3-dimeth-l-butene
3-methvlo9ntane
1-hexene; 2-ethvl-l-butene
fl-hexane; cis-3-hexena
2 methyJ-2-pentane
Methvl cvclooentane; 3-methtrans-2-oentene
2,4-dimethyloentane
MethyJ eye 1 oper.tsne
Benzene, cyclohexane
Cyclohexene; 2,3-dimethylpentane; 2-methvlhexana
3-methylhexane
. Isooctane
fl-he^tane
Methyl cyclohexane
2,4 and 2 ,5-dimethvlhexane
2,3,4-trimethyloentane
2,3,3-crimethvlpentane
Toluene; 2 ,3-dimethylhexane
2-methylheptane
3-me thy 1 heptane
2,2,5-trimethyJhexane
N-octane
2 ,3,5-trimethylhexane
2 ,4-dimethylheptane
2,5 and 3 ,5-dimethylheptane
Ethytbenzene; 2 ,3-dimethylheptane
P-xylene; m-xylene; 4-ethyl octane
0-xvlene; unk C9 paraffin
Nonane
N-propy 1 benzene
1-methyl 3-ethyl -benzene; unk Clo oaraffin
1-methyl 3-ethyl benzene; unk C)0 paraffin
Mesitylene
1 .2 ,4-triniethylbenzene
Secbutyl benzene; n-decane
Unknowns
NR
0
NR
NR
0
0
0
p
0
.8P/.20
0
0
0
P
0
.9P/.10
0
0
0
P
P
.94P/.060
P
0
P
0
.93P/.070
P
0
.5P/.5HR
.92P/.080
P
P
P
P
P
P
P
.02P/.9SA
P
P
P
P
P
P
P
.IP/.9A
.IP/.9A
.05P/.95A
P
A
.07P/.93A
.25P/.75A
A
A
.6P/.4A
.SP/.20
1
Z
i
2
3
3 -
1
*
M
H
^
4
3
0
5
5"
t3
3
0
-$/<*
(,
h
Id
b
b
to
-------
chromatograph peaks. The class and carbon number for each compound
are also listed. Some of these compounds peak, or elute, at the
same time on the gas chromatograph. It should be noted that the
percentage each compound contributes to a peak and the distribution
of the various classes of compounds are fuel related.
All of the data for the gasoline vehicles has been taken from a
paper written by F. Black and L. High of the Environmental Protection
Agency facility at Research Triangle Park, North Carolina . Indi-
vidual hydrocarbon emission rates were determined for 22 motor
vehicles, 18 of which will be presented here. The vehicle types and
the corresponding number tested are listed below.
Vehicle Type Number
Not catalyst-equipped 1
Catalyst-equipped 13
"lean-burn" without catalyst 4
Total 18
In this paper, emphasis is placed on catalyst, and to a lesser
extent, lean-burn systems since they currently dominate the ap-
proaches to emission control. Table 2 presents the data in terms of
class of compound, Table 3 in terms of carbon number, and Table 4 in
terms of individual components. The 1975 Federal Test Procedure
(FTP) was used in all emissions testing reported here. The samples
were collected using a constant volume sampler and analyzed by gas
chromatography coupled to a flame ionization detector. The gasoline
used for the catalyst and leanburn vehicles was a test fuel with a
Reid Vapor Pressure of 10.2 psi and was composed of 26.2% aromatics,
6.5% olefins and 67.3% paraffins.
A comprehensive paper was published by Marvin Jackson of General
Motor's Environmental Activities Staff entitled "Effect of Catalytig
Emission Control on Exhaust Hydrocarbon Composition and Reactivity" .
Data was presented in terms of carbon percent of total hydrocarbons.
Weight percents were not included and so the data is not presented
here. However, Marvin Jackson did convert Frank Black's data to
carbon percents so both sets of data could be compared directly.
Jackson's data agrees quite well with that reported by the EPA. The
few differences occur in the fuel-type hydrocarbons and, according
to Jackson, are probably caused by fuel composition differences.
From Table 2 it can be seen that vehicles equipped with oxidation
catalysts emit a higher percentage of methane in their exhaust than
do non-catalyst or lean-burn equipped vehicles. Most catalytic
converter systems preferentially oxidize non-methane hydrocarbons
because methane is harder for the catalytic converter to oxidize.
Methane is not a significant photochemical emission because it is
essentially non-reactive. Thus, the total photochemical reactivity
of the hydrocarbon (HC) mixture tends to be reduced by the catalyst.
In addition, the catalyst reduces the total hydrocarbon mass and
generally oxidizes the unsaturated HC compounds to a greater extent
than the saturated compounds.
-------
TABLE 2
VEHICLE
NON-CATALYST
1972 Chev. 350 CID
CATALYST
1975 Ply. Fury
318 CID
1975 Chev. Impala
350 CID
1975 Ford Granada
302 CID
1976 Ford Mustang
302 CID
1976 Ford LTD
400 CID
1977 Chrysler NY
400 CID
1977 Dodge
360 CID
1977 Ply. Fury,
318 CID
1977 Ply. Fury,
225 CID
1977 Chev. Nova,
305 CID
1977 Chev. Vega
140 CID
1977 VW Rabbit
1977 Audi Fox
AVERAGE
LEAN-BURN
1976 Cordoba
440 CID
1976 Ply. Fury
318 CID
Chrysler Imp. Prototype
440 CID
Chrysler Imp. Prototype
440 CID
AVERAGE
CONTROL
SYSTEM
Eng. MOD.
Oxidation
Catalyst
Oxidation
Catalyst
Ox. Catalyst
Air Pump
Ox. Catalyst
Air Pump
Ox. Catalyst
Air Pump
Ox. Catalyst
Air Pump
Ox. Catalyst
Air Pump
Ox. Catalyst
Air Pump
Ox. Catalyst
Air Pump
Oxidation
Catalyst
Ox. Catalyst
Pulsed Air
Oxidation
Catalyst
Oxidation
Catalyst
Electronic
Lean-Burn
Elec. Lean-
Burn
Air Pump
Electronic
Lean-Burn
Electronic
Lean-Burn
TOTAL HC
mg/mile
1150
490
250
920
550
630
260
230
330
840
620
230
180
270
450
660
1450
390
470
740
PERCENTAGE OF TOTAL HC, WT%
METHANE
9.3
9.4
15.5
4.8
15.3
14.7
26.2
29.7
18.8
14.4
14.9
18.3
18.7
14.5
16.6
3.7
2.8
4.8
3.5
3.7
PARAFFIN
40.6
61.8
57.1
68.1
56.6
63.9
68.0
67.3
60.9
58.0
50.7
61.1
64.0
55.3
61.0
34.2
43.5
29.5
34.5
35.4
ACETYLENE
11.0
2.0
2.7
0.5
3.4
3.3
2.5
2.2
4.4
3.4
9.5
1.9
2.9
1.7
3.1
8.1
4.7
11.1
9.8
8.4
"AROMATIC
22.3
18.9
19.7
14.7
19.5
15.8
11.8
15.5
16.9
18.6
21.4
17.7
18.7
22.6
17.8
24.2
23.6
19.9
19.7
21.9
OLEFIN
26.1
17.3
20.5
16.7
20.5
17.0
17.7
15.0
17.8
20.0
18.4
19.3
14.5
20.4
18.1
33.5
28.2
39.5
36.0
34.3
-------
TABLE 3
Gasoline Vehicle Hydrocarbon Emission Rates in Terms of Carbon Number
CARBON NUMBER
1
2
3
4
5
6
7
8
9
10
Unknowns
THC
NON-CATALYST
mg/mi
107
289
78
101
94
97
166
136
38
4
42
1150
wt.%
9.3
25.1
6.8
8.7
8.2
8.4
14.4
11.8
3.3
0.3
3.7
100.0
CATALYST
mg/mi
64
54
15
33
71
35
72
74
14
1
14
450
wt.%
14.3
12.0
3.4
7.5
15.9
7.8
16.1
16.5
3.2
0.2
3.1
100.0
LEAN-BURN
mg/mi
25
165
57
63
76
64
128
107
28
1
28
740
wt.%
3.4
22.3
7.7
8.5
10.2
8.6
17.2
14.4
3.8
°-\
- j\
100.0
ij
-------
FTP Hydrocarbon Emission Rates/ig/mi .*"
Non-Catalyst Catalyst Lean -Burn
1 Methane
2 Ethvlene
3 Ethane
4 Acetylene
5 Prcpylene; propane
6 Propadiene
7 Methyl acetylene
8 Isobutane
9 Butene 1; isobutylene
10 N-butane; 1 , 3-butadiene
11 Trans-2-butene
12 Cis-2-butene
13 3-methyl-l-butene
14 Isooentane
15 Pentene-1
16 Njientane; 2-methyl-l-butene
17 Trans-2^pentene
18 Cis-2-pentene
19 2-methyl-2-butene
20 Cyclopentane;3-methyl-l-pentene
21 2,3-dimethylbutane
22 2-methylpentane; 2,3-dimeth-l-butene
23 3-methylpentane
24 l-hexene-2-ethyl-l-butene
25 N-hexaneL cis-3-hexene
26 2 methyl -2-pentene
27 Methylcyclopentane; 3-rcethtrans-2-pentene
28 2Jl4-dimethyJi)entan9
29 Methyl cyclooentene
30 Benzene, cyclohexane
31 Cyclohexene: 2,3-d-iir.ethy ipentane; 2-methylhexane
32 3-methylhexane
33 Isooctane
34 N-heptane
35 Methylcyclohexance
36 2,4 and 2,5-dimethylhexane
37 2,3,4-trircethylpentane
38 2,3,3-trircethylpentane
39 TclueneL_2,3-dimethylhexane
40 2-rcethylhej)tane
41 3-methylheotane
42 2.2,5-trimetnylhgxane
43 fl-octane
44 2,3,5-tri-ethvlhexane
45 2 .4-dimethvlheotane
46 2,5 and 3.5-di,r.ethvlheotane
47 Ethvlbenzene; 2.3-direthvlheptane
48 P-xvlens^ m-xvlene: 4-n:ethyl octane
49 0-xvlene; unk Co paraffin
50 No nan?
51 fl-proDvl benzene
52 1-r.ethvl 3-ethvl -benzene ; unk CIQ paraffi'n
53 l-rethvl-2-ethvlben:ene; u;-1: CIQ paraffin
54 Xesi tvlene
55 1 ,2,4-trircethvlbenzene
56 Secbutylbsnzeno : n-decane
57 Unknowns
lO/o-^
1 M °( \
13.3
\21.Q
13.0
trctce
tracd.
9.2
n.i
faH.l
2.1
5.0
3.0
31.2
.9
2M.9
\.ia
.1
\ 0.3
M3.9
4.H
M.I
1.5-
.1
I.M
1.3
i.ia
1.9
2.8
51.0
1.2
trace
Ml.o
5.5"
2.2.
lo.l
2.1
2.5"
is I.M
1.lo
b.i
t-H
3-1
-1
-6
i-ifl
i 0.1
3M.2
i 5. i
3.1
i.Z
l,H
3.1
3.b
10.0
2.0
MZ.O
bM.I
2S.2
21, & 109. ft
1 l.o
H-M
1 5.0
.2.
1.3
"? 1
21.1
1.1
i.5-
.4
23.3
.3
5.0
5 I.M
O 3 .£>
,3
i- 1
M.H
23.i
2 M.I
fa. (a
M.i
1,9
2M-0
i-t
18.5 n.«t-
.q
1.2.
\i.i
11.0
2.3
2.H
1.3
,H
i.2
.6
/I
1.3
.1
iO.i
iS.3
3.4
30.5"
M.2
2.0
M.&
M.2
.4
m.^
b.o
M.e
1.3
:?M
1
.w
.d
3. a
i (.19
M.7
I.I
.«
2.(o
2.6-
:0.1.
2^.2.
2.5
5.0
2.3
i.q
a.a-
2.8
. 2.(o
2.0
jo
2 b.S"
i 8- to
5.6
3M.2.
4.H
3. fa
s.q
5.(o
--
a b-0!
fe.l
7.0
l.ia
3.y
. i
1
.&
I.M
m.ft
; j.io
9 -J
i-3
2.to H.4
.3 i
1.7
3. to
4.0
1.3
-7 .3
-.4.0 '11
TOTAL . 1150. HSC. 1MO.
-------
For the catalyst-equipped vehicles tested, the methane emissions
ranged from about 4.8 to about 29.7% of the THC with an average of
16.6%. For the vehicles using a lean-combustion emission control
system, the methane emissions ranged from about 2.8. to about 4.8% of
the THC with an average of about 3.7%. It appears that lean-com-
bustion is not as effective as oxidation catalyst control in reducing
the amount of unsaturated hydrocarbons in the exhaust. The relative
abundance of olefins in lean-combustion exhaust (34.3% of THC) was
significantly higher than in catalyst exhaust (18.1% of THC). The
aromatic level was 21.9% with lean-combustion and 17.8% with cata-
lysts. Acetylene averaged 8.4% with lean-combustion and 3.1% with
catalysts. In contrast, the paraffin level (composed of saturated
hydrocarbons) averaged 61.0% for the catalysts and only 35.4% for
the lean-combustion exhaust. The total hydrocarbon mass was higher
for lean-combustion equipped vehicles (450 mg/mile THC for the
catalyst and 740 mg/mile THC for the lean-burn system). Figure 1
graphically illustrates the data.
Table 3 presents the data in terms of carbon number. The most
apparent differences in hydrocarbons emitted under the 3 control
options occur at carbon numbers 1, 2 and 5. These differences can
at least be partially accounted for by the ability of the catalyst
to oxidize unsaturated hydrocarbons. Table 4 presents a more de-
tailed hydrocarbon comparison. The lean-burn equipped vehicles
emitted less total hydrocarbon and their exhaust hydrocarbon mixture
was lower in photochemical reactivity than the non-catalyst-equipped
vehicles. It is evident that the hydrocarbon composition of tail-
pipe emissions is sensitive to the emission control system used.
The emission data presented here represents the case for vehicles
run under ideal operating conditions. It should be noted that
in-use vehicles may not have the same emissions due to mis-fueled or
poorly maintained vehicles, different driving cycles and different
temperatures.
B. Evaporative Emissions and the Effect of Fuel Composition
Hydrocarbon composition is significantly different in tailpipe and evapo-
rative emissions.. The information and data used for the evaporative
emission analysis was taken from another paper by F. Black, et.al. . The
details of the vehicle preconditioning, diurnal evaporative test, cold
start exhaust test, and hot soak evaporative test are given in the Federal
Register.
Evaporative sources constitute, typically, 30 to 60 percent of the total
hydrocarbon emissions from passenger gasoline vehicles with catalysts.
The vapor pressure of most current Diesel fuels under ambient conditions
is so low that Diesel evaporative emissions are very low. Diesel equipped
vehicles are not currently subject to evaporative emission requirements.
-------
feO
50
40
o
a:
30
10
EFFECT
FIGURE
Co*my>»- SYSTEM ON E*H*OST
..... ........ - NOlJ -
A
MOO
foo
too
500
Moo .
-------
The evaporative emissions were found to be sensitive to the fuel
composition and the vapor pressure of the fuel. All of the emitted
hydrocarbons were greater than carbon number 4, normally the lowest
molecular weight component of gasoline. A list of the test fuel
specifications is given in Table 5. Four primary fuels were used.
Fuels A and C were regular grade unleaded, summer and winter, re-
spectively. Fuel B was a premium grade summer unleaded and Fuel D a
regular grade winter leaded. Fuels A-l, B-l and D-l had increased
benzene levels but did not differ in any other respect. These latter
fuels were used to examine the sensitivity of fuel benzene content
to benzene emissions. (These results and a complete analysis of
benzene emissions from both Diesel and gasoline vehicles will be
discussed in a later section.)
A summary of the results can be found in Table 6. Fuel C is the
most similar in composition to the fuel used for comparison of
catalyst, non-catalyst and lean-burn control systems in the previous
section.
Evaporative sources constituted a significant fraction of the total
vehicle aggregate hydrocarbon emissions, varying from about 1/3 to
1/2 with the vehicles tested. Evaporative emissions varied sig-
nificantly with the Reid Vapor Pressure (RVP) of the fuel. As the
RVP increases, the evaporative emissions also increase. Evaporative
emissions, as mentioned before, are dominated by fuel hydrocarbon
components. For this reason, they contain a greater abundance of
low molecular weight paraffinic hydrocarbon compounds than do exhaust
emissions. Increased aromatic content of the fuel caused increased
aromatic content in both the tailpipe and evaporative emissions.
High fuel vapor pressure generally resulted in increased paraffinic
content of the emissions, resulting from the use of low molecular
weight paraffins (butanes and pentanes) to increase fuel vapor
pressure. As mentioned previously, evaporative emissions increase
as the vapor pressure of the fuel increases. The trend in marketed
gasolines during the last 30 years has been to increase vapor pressure.
The relative proportion of evaporative hydrocarbon emissions has,
therefore, also been increasing and should be considered when ex-
amining hydrocarbon emissions from gasoline vehicles.
-------
10
TABLE 5
Test Fuel Specifications for Evaporative Emission
RVP
API Gravity
Distillation, °F
10%
50%
90%
EP
Hydrocarbon, Wt.
n-butane
i-pentane
n-pentane
benzene
toluene
paraffinic
olef inic
aromatic
1 leaded
2 analysi
A
Summer
8.4
61.6
133
207
285
376
%2
3.73
6.94
5.48
0.28
17.55
65.4
7.2
27.4
gasol ine
s by gas
FUEL CODES
A-l B B-l
Premium Summpr ui
9.8
54.9
126
219
327
369
3.48
11.19
3.40
7.1 1.52 7.1
27.91
49.0
7.6
43.4
1.98 g/gal.
chromatography
Analysis
C
i. .
12.3
62.0 '
114
219
362
410
9.94
7.85
4.13
1.95
6.30
67.0
7.0
25.7
D1 'D-1
Win tor
12.8
62.3
108
217
347
413
9.85
8.15
4.08
1.83 5.8
6.01
69.0
5.1
25.9
-------
TABLE 6
Tailpipe and Evaporative HC Emissions
Tailpipe HC Composition
% of Total
Evaporative HC Composition*
% of Total
THC
Vehicle Fuel (RVP) Paraffinic Olefinlc Aromatic Acetvlenic me/mile
% of Total
Aggregate THC
THC Paraffinic Olefinlc . Aromatic me/mile
% of Total
Aggregate Aggregate
THC THC me/mile
1963 D (12.8)
Chevrolet
1977 B (9.8)
Mustang C (12.3)
1978 A (3.4)
Monarch B (9.8)
C (12.3)
1979 B (9.8)
LTD-11 C (12.3)
42.0
43.2
54.7
60.8
56.0
63.7
58.3
72.8
27.1
16.0
21.6
18.6
13.9
18.6
10.9
11.6
20.7
40.7
23.4
20.1
28.7
14.2
29.9
11.0
10.2
0.2
0.3
0.5
1.4
3.5
0.9
4.6
4000
2800
2800
1000
900
1300
500
500
42
52
44
83
64
62
63
17
87.6
75.1
82.4
80.1
61.0
88.0
57.1
89.9
8.1
11.5
11.4
8.7
10.1
7.3
8.1
7.7
4.3
13.4
6.1
11.2
28.9
4.7
34.8
2.4
5600
2600
3600
200
500
800
300
2400
58
48
56
17
36
38
37
83
9600
5400
6400
1200
1400
2100
800
2900
*There is no acetylene in evaporative emissions.
EVAP
Pi + 3.3 trips/day (Hs)
29.4 miles/day
Where:
EVAP * Total evaporative emissions, grams/mile.
Di = Diurnal evaporative emissions, grams/day.
Hs ' - Hot soak evaporative emissions, grams/trip.
-------
12
III. Vehicles Equipped With Diesel Engines
Organ!cs emitted from vehicles equipped with Diesel engines range from C
to about C,», the majority being below C _. The C -C .. hydrocarbons
result almost entirely from the combustion process, which involves crack-
ing, and possibly polymerization, of higher molecular weight materials.
It is postulated that the C..n-C hydrocarbons result, to a large extent,
from uncombusted fuel, ana the C ,-C... hydrocarbons from lubricants.
It is possible to identify the individual components of carbon numbers 1
through 10 with a gas chroma to graph. The gas chromatograph used to
measure the compounds with carbon numbers greater than 10 does not have.
adequate resolution to permit identification of each individual compound
in this range. It is, however, possible to determine the molecular
weight distribution of the compounds of interest. Since it is not currently
possible to identify individual components of Diesel equipped vehicle
exhaust, Diesel hydrocarbon analyses must be done in terms of carbon
number.
The data used was taken from an EPA paper by F. Black . The Diesel-
equipped vehicles tested were prototypes, an Oldsmobile, a Nissan and a
turbocharged Rabbit. The data was presented in terms of relative a-
bundance of carbon number. We converted the data to units of milligram
per mile for each carbon number. (These calculations can be found in the
Appendix.) The fuel composition was 66.2% paraffin, 1.3% olefin and
32.5% aiWatic. The 1975 Federal Test Procedure was used.
\\
In the case of gasoline fueled vehicles, the hydrocarbon exhaust emissions
are low molecular weight hydrocarbons and are virtually all in the gas
phase at 125°F. These gaseous hydrocarbon emissions have routinely been
measured with the total hydrocarbon flame ionization detector (FID) and
exhaust samples collected in teflon film bags using a constant volume
sampling (CVS) system. However, measurement of exhaust hydrocarbons from
Diesel-equipped vehicles is much more difficult than with gasoline vehicles.
This is due, in part, to the high molecular weight hydrocarbons present
in Diesel exhaust. The teflon film bags used for gasoline vehicles
cannot be used for the higher molecular weight gaseous hydrocarbons in
Diesel exhaust because these heavy gaseous hydrocarbons are lost to the
walls of the bags and other cool surfaces contacted on transport from the
vehicle. The situation is further complicated by the fact that some of
the hydrocarbons emitted from Diesels are associated with carbon parti-
cles, often referred to as particle-bound organics (PBO). The particle-
bound organics are high molecular weight compounds. Diesel organic
emissions, therefore, occur in two physical states, gaseous and par-
ticulate, and contain high molecular weight hydrocarbons.
A diagram of an experimental gaseous and particulate emissions sampling
system for Diesel-equipped vehicles used in an EPA research project can
be found in Figure 2 . The dilute exhaust is processed in two temper-
ature regimes, at or below 52°C (125°F) and at 190°C (375°F). The measure-
ment of total hydrocarbons is made in the hot sample stream. Heating
-------
DISCHARGE
J3_
MANOMETER
i
I DILUTION AIR FILTER
1 SAMPLING TRAIN
D
AMDIENT AIR INLET
HOT FID
HOT PARTICLE FILTER
COOL PARTICLE FILTER
lr
OPTIONAL FOR
I PAIMICULAIE
. I PACKQROUND READING
ZERO AIR
COl/UTERS
0 BACKGROUND SAMPLE BAG
3 WAY
VALVE
READ OACKGROUND OAQ
r^
. DILUTION TUNNEL
HEATED PRODE
PARTICULATE PROOE
I MIXING ORIFICE
ABSOLUTE
PflESSURE
TRANSDUCER
HC SPAN GAS
HEATED SAMPLE LINE m
TO OUTSIDE VENf
t
RECORDER
HEATED PRODE
315°F
TO EXHAUST SAMPLE UAQ
MAX
CRlllCAL FLOW
VENTUni
PRIMARY FILTER (PHASE 2)
PACK UP FILTER
(PHASE
VEHICLE EXHAUST INLET
PRIMARY FILTER (PHASE I AND 3)
OACK-UP FILTER (PHASE t AND 3)
NOTE: THREE FILTER HOLDERS
(ONE FOR EACH PI IAS EJ
ARE ALSO ACCEPTABLE
CVS
I COMPRESSOR
DISCHARGE
FIGURE 2
GASEOUS AND PARTICULATE EMISSIONS SAMPUNQ SYSTEM (CFV-CVS)
(FOR DIESEL VEHICLES ONLY)
-------
14
the sample stream to 375°F causes desorption of most of the particle-
bound organics. Any particles present in the hot sample stream are
filtered at point (2), the hot particle filter, and solvent extracted.
The gaseous element of the hot sample stream continues through point (2)
and-is detected at point (1), the heated FID. The quantity of hot filter
extractables is a very small percentage compared to the hydrocarbon
heated FID measurement. The cool particle filters, located at point (3),
are solvent extracted to determine the emissions of particle-bound
organics. The 125°F gas phase hydrocarbons downstream of the cool parti-
cle filter are the hydrocarbons of interest in this report and will
hereinafter be referred to as gas phase organics (at 125°F).
The hot filter extractables plus the heated FID measurement are quanti-
tatively compared with the cool filter extractables to obtain by differ-
ence the gas phase organics (at 125°F). Figure^ 3 summarizes the hydro-
carbon analysis performed by Black and High . The total hydrocarbon
emissions in this experimental set-up can be considered to equal the hot
FID measurement plus the hot filter extractables (HFE), A+C. The total
particle-bound organics are determined by solvent extraction of the cool
filters, D. The total gas phase organics can be determined by subtracting
D from A+C. The total gas phase organics (at 125°F) are thus equal to
the hot FID measurement (A) plus the hot filter extractables (C) minus
the cool filter extractables (D) (hot FID+HFE-CFE). The measurement of
gas phase organics is based on the assumption of conservation of
organics, i.e. the organics in the hot filter stream are assumed to equal
the organics in the parallel cool filter stream. Referring again to
Figure 3, the total organics in the hot filter stream are equal to A+C.
The organics in the cool filter stream are equal to D plus the gas phase
organics (at 125°F). Equating the organic streams and isolating the gas
phase organics gives: total gas phase organics (at 125°F) = A+C-D. The
molecular weight distribution of the gas phase organics (at 125°F) are
determined with gas chromatographic analysis of samples B, D and E. The
gas phase organics (at 125°F) distribution is equal to B+E-D which gives
the carbon distribution from C 1,, and C _ ,^.
Black and High determined the total gas phase organics (at 125 °F) by
difference with the cool particles rather than using an FID directly
behind a cool filter because of anticipated difficulty in transporting
the high molecular weight gaseous organics through cool (at or below
125°F) plumbing which has a high ratio of surface area to volume. In
contrast to the particle-bound organics, the gas phase organics (even at
125°F) from Diesel vehicles may be susceptible to wall interaction.
Research with multiple FIDs and alternate sampling systems has been
performed in the past. Two FIDs were used during a light-duty Diesel
particulate baseline study at the EPA/MVEL facility in Ann Arbor . The
two instrument approach is difficult because of the problem of variable
instrument response.
Black and High have conducted experiments with a Nissan Diesel involving
multiple tests with a single hot FID with and without a cold filter
-------
F GURE 3
HYDROCARBON! ANALYTICAL
SCHEME
DILUTE DIESEL
HYDROCARBON EMISSIONS
315° F
I25°F
H
PAR!
FR
HOT FID
(A) (i
CONTINUOUS po
THC-F1D POl
(ELECTRONIC T
INTEGRATIOH)
MASS M6
T
EXTRA
3T
riCLE )
TER
HF
3) (C
RODS Me
.WER, PART
KAP EXTRA
Clz.
RAP
CTIOM
E CF
? (1
C12 Me
1CLE PAR!
CTIOM EYTRA
1 GRAVIMETRIC
MASS
COOL
1 ( PARTICLE
FILTER
1
E GAS PHASE
ORGANICS
5) (§
Clz.
1 /^l C
lCLt TEFLON
CTIOM BAGr
GRAVIMETRIC
MASS
GAS GAS r,k
£AS CHROMATOGRAPHY
CHROMATOGRAPHY
CHROMATOGRAPHY
CHflOMATOGRAPHY
A' HOT FID- HEATED FLAME 10MI7ATION DETECTOR
C' HFE- HOT FILTER EXTRACTABLES
CFE^ COOL FILTER EXTRACTABLES
GAS PHASE ORGAHICS- A
-------
16
standard hot FID system was used to measure THC followed by determination
of THC emissions with the same hot FID but with a pallflex (teflon coated
glass fiber) filter on the inlet to the sample probe inside the tunnel.
The average of three FTP tests were determined for each configuration.
The difference between the measurement obtained without a filter (THC)
and the measurement obtained with a filter (gas phase organics at 125°F)
is an indication of the particlebound organics. The results obtained by
this difference procedure indicate that 16.1% of the THC emissions were
particle-bound. The particle-bound organics measured by methylene chloride
extraction of the particles collected on the pallflex filters (26°C
or 79°F) indicate 16.6% of the THC was particle-bound. These values
agree very well. However, a system such as this would require duplicate
runs and may not be practical for certification purposes.
Table 7 lists the carbon number distribution for each of the three Diesel
equipped vehicles and also includes the averaged values from the three.
From this data it is evident that gas phase organics at 125 °F in Diesel
exhaust have a wide carbon number distribution and contain small quanti-
ties of high molecular weight organics. Approximately 60 to 85 percent of
the total hydrocarbons in Diesel exhaust are associated with the gas
phase at 125°F which means 15-40% of the hydrocarbon compounds are not in
the gas phase at 125°F. (We would once again like to emphasize that, for
the Diesel-equipped vehicles, we are discussing gas phase organics at
125°F, i.e. the measurement of heated FID plus hot filter extractables
less cool filter extractables. Gas phase organics in Diesel exhaust are,
for the sake of this paper, considered to be those organics in the gas
phase at or below 125°F.) The Diesel equipped Rabbit emitted the lowest
mass, followed by the Oldsmobile and the Nissan which emitted more. The
emissions were approximately 244, 273, and 295 mg/mile respectively, as
measured by the aforementioned procedure. To put this data in proper
perspective, it will be compared with carbon number data from catalyst-
equipped vehicles.
IV. Diesel-Equipped vs. Catalyst-Equipped Vehicles
Tables 3 and 7 can be used to compare gas phase carbon number data for
the light-duty gasoline and Diesel-equipped vehicles. It should be kept
in mind that 13 vehicles equipped with catalysts were used in this analy-
sis in contrast to only 3 vehicles equipped with Diesel engines. Neither
the prototype Diesel equipped vehicles nor the catalyst-equipped gasoline
vehicles were designed to meet the 1980 0.41 g/mile total hydrocarbon
emissions standard. Unfortunately, the available information is limited
to older vehicles. The data presented may not be representative of more
recent production models; however, it is likely reflective of current
on-roadway conditions.
Based on average values, the Diesel-equipped vehicles have higher mole-
cular weight gaseous organics but emit lower emissions (approximately 270
mg/mile for the Diesels, 450 mg/mile for the catalyst-equipped vehicles).
The higher hydrocarbon mass for the catalyst-equipped vehicles is partially
attributable to a greater percentage and mass of methane in the catalyst
exhaust (14.3% methane in the catalyst exhaust compared to 6.5%
in the Diesel exhaust).
-------
17
TABLE 7
Carbon Number Data for Diesel-Equipped Vehicles
Carbon Number ,, . , .
We! ic he ot C.is Pn;is
-------
18
Diesel engine exhaust, including gas phase organics and particle-bound
organics tends to be heavier than gasoline-catalyst exhaust. This is due
mainly to the hydrocarbon fraction with carbon numbers C _- C r. These
tend to contain a high percentage of aromatics which are of concern as
some members of this class of compound have been found to give positive
results in initial bioassay screening tests for carcinogenicity. To date,
samples examined for mutagenicity/carcinogenicity have consisted of
organics extracted from particulate material. Methods for collection of
the gas phase organics are not sufficiently developed at this time to
allow direct bioassay testing of gaseous material. Nevertheless, the
presence of these heavier, higher molecular weight compounds in Diesel
exhaust cannot be overlooked as these compounds have not all been iden-
tified and may pose health risks.
Figure 4 compares gaseous hydrocarbon emissions by carbon number for a
gasoline fueled VW Rabbit with an oxidation catalyst and a prototype
turbocharged VW Rabbit equipped with a Diesel engine. Data for the
Diesel-equipped Rabbit can be found in Table 7, for the catalyst-equipped
Rabbit in Table 8. Figure 4 provides a direct and easier comparison for
each carbon number. The VW gasoline Rabbit emitted 180 mg/mile in com-
parison to 240 mg/mile for the Diesel-equipped Rabbit. In this case, the
Diesel gaseous emissions were approximately 33% higher. The Diesel
emitted more gaseous compounds of carbon numbers 2, 3, 6, and 10 or
greater. The gasoline Rabbit emitted more compounds of carbon numbers 1
(methane), 4, 5, 7, 8, and 9. The Diesel-equipped vehicle consistently
emits a greater percentage of heavier, unidentified hydrocarbons in its
exhaust. As mentioned previously, this is significant as one or more of\
these compounds may be carcinogenic.
V. Carcinogenicity - Benzene Emissions . '
Benzene has been determined to be a hazardous pollutant and a potential
carcinogen. Benzene is present in both gasoline and Diesel exhaust and,
in addition, in gasoline evaporative emissions. Because of benzene's
association with cancer, it is of importance to examine the emission
rates of benzene from gasoline and Diesel-equipped vehicles.
Table 9 presents benzene data from one non-catalyst and three catalyst-
equipped vehicles. Both tailpipe and evaporative benzene emission rates
are included. These are the same vehicles and fuels used for the evapo-
rative emission analysis. (When comparing fuels it should be noted that
typical commercial gasoline benzene content is less than 2 percent.
Diesel fuel contains insignificant levels of benzene.)
Benzene emissions reflected both fuel benzene and fuel total aromatic
content. The fuel benzene level had a more pronounced impact on evapora-
tive emission rates than tailpipe rates. This is expected because the fuel
is the only source of benzene in evaporative emissions whereas the combus-
tion process is a significant additional source in tailpipe emissions.
Under normal operating conditions evaporative benzene accounted for 20 to
30% of the total aggregate benzene emissions. Both tailpipe and evaporative
-------
19
TABLE 8
Carbon Number Data for the Catalyst-Equipped VW fldbblt
Carbon Number
1
2
3
4
10
Unknowns
Total
Weight, mg/mile
34
18
5
12
34
29
29
0.6
5
180
Compounds
methane
ethylene, ethane, acetylene
propylene, propane
isobutane, butene-1, isobutylene
n-butene, 1,3-butadiene, cis-2-butene
isopentane, pentene-1, n-pentane,
2-methyl-l-butene, trans-2-pentene,
cis-2-pentene, 2-methyl-2-butene,
cyclopentane
2,3-dimethylbutane, 2-methylpentane,
2,3-dimethyl-l-butene, 3-methylpentane,
1-hexene, 2-ethyl-l-butene, n-hexane,
cis-3-hexene, 2-methyl-2-pentene,
methylcyclopentane, 3-methtrans-2-
pentene, 3-methyl-l-pentene, cyclohexene,
benzene, cyclohexane
2,4-dimethylpentane, 3-methyIhexane,
n-heptane, methylcyclohexane, 2,3-
dimethylpentane, 2-methyIhexane, toluene
/'
isooctane, 2,3-, 2,4- and 2,5-dimethylhexane,
2,3,4-trimethylpentane, 2- and 3-methyIheptane,
n-octane, ethylbenzene, p-, o- and m-xylene
2, 2, 5-trimethylhexane, 2,3-, 2,4-, 2,5- and
3,5-dimethyIheptane, nonane, n-propylbenzene,
4-methyloctane, unknown Cq paraffin, 1-methyl-
3-ethylbenzene
secbutylbenzene, n-decane, unknown
C paraffin
-------
FIGURE M
Compdrdtive Emissions of Gas Phase Hydrocdrbons from Two vW Rabbits
in? vw Rdbbit with oxiddtion catalyst
Turbocharqed Rdbbit with Diesel engine.
50
cr>
30
50
o
O MO
D
X 30
10
10
15
Data presented for each vehicle, individually
vw Rdbbit with oxidation catalyst
10
NUMBER
30
Turbocharqed Rdbbit with Diesel enqme.
IS 20
CARBON NUMBER
30
35
-------
Table
Passenger Car Benzene Emissions
Vehicle
1963
Chevrolet
1977
Mustang
1978
Monarch
1979
LTD- 1 1
Fuel
Code Aromatic, % Benzene, %
D 25.9 1.8
D-l 28.9 5.8
B 43.4 1.5
B-l 46.6 7.1
C 25.7 2.0
A 27.4 0.3
A-l 32.4 7.1
B 43.4 1.5
C 25.7 2.0
B 43.4 1.5
B-l 46.6 7.1
C 25.7 2.0
Tailpipe Benzene
Mg/n»1 % of
aeerep.ate
153
327
292
397
190
30
58
30
33
25
35
14
az.
b3
8b
13
11
n
84
11
ft!
ie>
\o!L
54
Evaporative Benzene
Mg/mi % of
npprpp.nfp
33
192
48
146
58
1
11
9
5
7
21
12
19
31
IM
21
23
3
|(o
23
\3
22.
30
Mb
Aqqreq."
Mg/n
186
519
340
543
248
31
69
39
38
32
56
26
-------
22
benzene increased with increasing benzene content of fuel. Fuel aromatic %
also influenced both tailpipe and evaporative benzene. Tailpipe benzene rates
were higher with the higher aromatic fuels. There was also an increase in
benzene in tailpipe emissions under rich combustion conditions.
Table 10 presents a general summary of benzene tailpipe emissions from catalyst
and Diesel-equipped vehicles. Data for the catalyst-equipped vehicles was
based on 15 vehicles while only 8 vehicles were tested for the Diesel analysis,
Benzene and cyclohexane peak at the same point on the gas chromatograph. The
percentage each compound contributes to this peak for the catalyst-equipped
vehicles is dependent on the fuel used. In this case,for the catalyst-equipped
vehicles, the peak is composed of approximately 50% benzene and 50% cyclohexane.
The benzene data for the Diesel-equipped Oldsmobile, Nissan and Turbo-Rabbit
was presented as a percentage of the total hydrocarbon measurement (for these
vehicles total hydrocarbons can be considered to equal the hot FID measurement
plus the hot filter extractables). Benzene constitutes one of the gas phase
organics in Diesel exhaust. Benzene has not been found bound to particulate
matter.
The highest emitter of tailpipe benzene was the 1978 gasoline Monarch with an
emission rate of 33 mg/mile. Evaporative benzene can account for up to 20 to
30% of the total aggregate benzene from gasoline vehicles and is an additional
factor that should be kept in mind when examining gasoline benzene emissions.
Unfortunately, there was not enough data to include this type of information
here. The catalyst-equipped vehicles emitted from 1.1 to 2.8 percent of their
tailpipe hydrocarbons as benzene.
The Diesel data were similarly scattered; the Diesels emitting 0 to 3.8 percent
of their tailpipe hydrocarbons as benzene. The Mercedes 220D Comprex emitted
a low mass of benzene and total hydrocarbons, yet had the greatest percentage
of benzene in its hydrocarbon exhaust (3.8%). In contrast, the Mercedes 240D
and the Peugeot 204D had no benzene in the exhaust. As a rough comparison,
tailpipe benzene emission rates vary from 0 to 15.4 mg/mile for the
Diesel-equipped vehicles and from 2.4 to 33 mg/mile for the catalyst-equipped
vehicles, based on this data.
Summary
1. Gas phase hydrocarbon emissions from light-duty gasoline and Diesel-
equipped vehicles were examined and compared. The hydrocarbon compo-
sition of gasoline exhaust consists primarily of components of carbon
numbers 1 through 10. In contrast, the gas phase organics from vehicles
equipped with Diesel engines range from C to about C,n» and contain
small quantities of high molecular weight organics.
2. The hydrocarbon data presented for the Diesel-equipped vehicles were
limited to three vehicles. In contrast, individual hydrocarbon data for
13 catalyst-equipped vehicles were available. The catalyst-equipped
vehicles were well tuned and thus may not always.represent in-use vehicles.
These factors should be taken into consideration when evaluating the
results.
-------
23
TABLE 10
PASSENGER CAR BENZENE EMISSIONS FOR CATALYST-EQUIPPED AMD DIESEL-EQUIPPED VEHICLES
Vehicle
Fuel Tailpipe Benzene
% Aromatics rng/mile
Tailpipe THC
mg/mile - % Benzene
Catalyst
Average of
13 vehicles
From Table 2
197"8 .Monarch3
1979 LTD II3
Diesel
Oldsmobile 5
Nissan
Turbo-Rabbit
Q
Mercedes 220D
Mercedes 2400^
Mercedes 300D*1
Peugeot 204D°1
Perkins 6-247^
26.2
25.7
25.7
32.5
32.5
32.5
25.6
25.6
25.6
25.6
25.6
c -i Min. 2.4
Max. 11.8
33
14
:i3.4
9.4
2.4
9.8
0.0
4.0
0.0
15.4
450 Min. 130
Max. 920
t
1300
500
450
350
290
260'
210
160
160O
720
Min. 1.3
Max. 1.3 .
/
2.5
2.8
3.0
2.7
.83
3.8
0.0
2.5
0.0
2.1
NOTE: The numbers 1, 3, 5, and 9 refer to the numbered references given
at the end of this paper.
THC values for the Diesel-equipped Oldsmobile, Nissan and
Turbo-Rabbit include both hot FID and hot filter extractables.
The 1975 FTP was used for every vehicle.
-------
24
3. The catalyst tends to oxidize the unsaturated hydrocarbon compounds to a
greater extent than the saturated compounds. Methane is a saturated
compound and, because of its refractory nature, is the least oxidized
compound. This explains the high percentage of methane in exhaust -from
vehicles equipped with catalysts. The Diesel, in turn, appears to have a
greater percentage of unsaturated hydrocarbons such as olefins and aro-
matics in its exhaust.
4. Further detailed hydrocarbon comparisons are hampered by the lack of
data on higher molecular weigfrt organics in the exhaust from Diesel-
equipped vehicles. One or more of these unidentified high molecular
weight organics may be carcinogenic.
5. Available data indicated that exhaust gaseous benzene emissions from
gasoline catalyst-equipped and Diesel-equipped vehicles are roughly
equivalent. Additional evaporative emissions of benzene (which occur
from gasoline vehicles 'but not Diesel-equipped vehicles) may be as high
as 50% of the exhaust emissions based on limited tests run to date.
6. The collection of data on individual components of exhaust and evapo-
rative emissions is significant in that individual carcinogenic potency
can be examined. Identification of emissions by structure or class of
compound is useful but ignores individual potency that may be important.
7. Some of the hydrocarbons in Diesel-equipped vehicle exhaust are of high
molecular weight. These heavy exhaust hydrocarbons are found both in the
gas phase and bound to particulate matter. While extensive Ames bioassay
testing for mutagenicity is being performed on the organics extracted
from the particulate, the relative mutagenicity of the gas phase organics
remains unknown. To date, no method exists to collect gas phase hydro-
carbons in exhaust for bioassay testing although work is in progress to
develop such a method.
-------
25
References
1. F. Black and L. High, "Automotive Hydrocarbon Emission Patterns in
the Measurement of Nonmethane Hydrocarbon Emission Rates", SAE
770144.
2. M. Jackson, "Effect of Catalytic Emission Control on Exhaust
Hydrocarbon Composition and Reactivity", SAE 780624.
3. F. Black, L. High and J. Lang, "Composition of Automobile Evaporative
and Tailpipe Hydrocarbon Emissions", draft. The published version
contains individual hydrocarbon data for the evaporative emissions
and is entitled "Passenger Car Hydrocarbon Emissions Speciation",
EPA-600/2-80-085, May 1980.
4. Federal Register, "Final Evaporative Emission Regulations for Light-Duty
Vehicles and Trucks", Vol. 41, No. 164 (August 23, 1976).
5. F. Black and L. High, "Methodology for Determining Particulate and
Gaseous Diesel Hydrocarbon Emissions", SAE 790422.
6. Federal Register, "Standard for Emission of Particulate Regulation
for Diesel-fueled Light-Duty Vehicles and Light-Duty Trucks",
Vol, 45, No. 4^5 (March 5, 1980).
7. Private communication with Eugene Danielson, EPA, Ann Arbor, Michigan
July 1980. Daka contained in Technical Support Report SDSB 79-03,
"Particulate Measurement-Light-Duty Diesel Particulate Baseline Test
Results", January 1979.
8. F. Black and L. High, "Diesel Hydrocarbon Emissions, Particulate and
Gas Phase", presented at the Symposium on Diesel Particulate Emissions
Measurement and Characterization, May 17-18, 1978, Ann Arbor, Michigan.
9. K. Springer and R. Stahman, "Diesel Car Emissions - Emphasis on
Particulate and Sulfates", SAE 770254.
-------
26
Appendix
The carbon number data for the Diesel-equipped vehicles was given in
terms of relative abundance. The heated FID, cool filter extractable
and ho,t filter extractable emission rates were given in units of
g/mile . Table A-l lists the relative abundances for each carbon
number. Once the relative abundances were available for each carbon
number for the hydrocarbons of interest, the carbon number data was
converted to emission rates in units of mg/mile (see Table A-2). In
this way, the data was in a form that could be directly compared to
data from gasoline catalyst-equipped vehicles. The method of calcu-
lation is included in this appendix. All figures in the Appendix
and in Tables A-l and A-2 come from reference 6.
-------
27
TABLE A-1
ct
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24 .
25
26
27
28
29
30
31
32
33
34
35
36
37
33
39
40
41
42
' 43
44
45
TOTAL
Conve rs ton
: OLDS
relative
(ht
CP
2.1
6.88
1.75
1.35
.95
1.55
.65
.65
.4
.5
.6
.65
1.0
1.3
1.45
1.25
.85
.5
.35
.25
.15
.15
.15
.05
.1
.05
.05
.05
.05
.05
.1
.05
.01
.02
.05
.02
.02
.05
.1
.02
.05
.02
01
26.35
10.
ntUMWt AOl
abundance
. ca]
Parclculace
.05
.15
.25
.35
.6
.75
.8
.6
.45
.4
.45
.5
.65
.75
.85
.95
1.0
1.0
1.0
.85
.9
.9
.85
.8
.6
.45
.35
.25
.2
.15
.1
.02
17.97
u
JNUAINCt. Ufrl
NISSAN
relative
Int.
CP
2.1
5.9
1.55
1.4
.7
1.35
1.35
.4
.3
2.4
2.2
.95
1.2
1.85
1.25
.95
.95
.55
.45
.2
.2
.15
.05
.1
.1
.01
.05
.05
.1
.1
.1
.1
.05
.05
--
29. 60
10
A
abundance
CO)
Paniculate
.03
.03
.05
.07
0.1
.15
.2
.35
.5
.6
.5
.45
.35
.25
.25
.25
.2
.15
.15
.1
.1
.1
.1
.1
.1
.07
.03
.02
.02
7.62
.1
TURBO-CHARGED
RABBIT
relative
(he.
abundance
cml
r.P Paniculate
1.2
5.78
1.55
1.05
.55
1.1
0.7
.4
.35
.45
1.0
1.0
1.35
1.05
1.05
.85
.65
.4
.35
.2:
.25
.3
.3
.35
.15
.25
.03
.2
.07
.1
.1
.1
.05
.12
.05
23.7
10
.03
.05
0.1
a2
.35
.45
.5
.45
.4
.35
.35
.35
.25
.3
.2
.15
.1
.15
.05
.05
.03
.02
.02
.02
4.92
.3
froa P. Slack 4 L. Hlch
SAE
-------
TABLE A-2
RELATIVE ABUNDANCE CONVERSIONS AND CALCULATIONS
OLDS NISSAN
A. Given Values (mg/mile)
HFE = hot filter cxtractables
HOT FID = heated flame ionizatior detector
CFE - cool filter extractables
(Hot FID + HFE - CFE) = diesel hydrocarbon measurement
of interest
11
445
181
275
8
349
58
299
RABBIT
3
292
50
245
Bl Calculated Values (mg/mile)
GPn « [-RA§-] x (Hot FID + HFE - CFE)
where:
GPn = weight of (Hot FID + HFE - CFE) hydrocarbons
of carbon number n, mg/raile
RAn = relative abundance of (Hot FID + HFE - CFE)
component of carbon number n
RAg = total relative abundance of (Hot FID + HFE - CFE)
component
(Hot FID i HFE - CFE)
=275 mg/mile
RAg=26.35
/. GPn=10.4 (RAn)
(Hot FID + HFE - CFE)
=299 mg/mile
RAg=29.66
.'. GPn=10.1 (RAn)
(Hot FID + HFE - CFE)
=245 mg/mile
RAg=23.7
00
/.GPn=10.3 (RAn)
C. Sample Calculation For
RA1Q X (Hot FID + HFE - CFE)
GP10-10.4 (RA1Q)
RA1Q= 0.5
GP=5 mg/mile
GP1Q-10.1 (RA1(J)
RA1Q = 2.4
.'.GP10=24 mg/mile
CP10=10.3 (RA1Q)
RA1Q = 0.4
GP=4 mg/raile
(These numbers can be compared with those in Table 7.)
------- |