EPA-420-S-78-100
78-l34."5
Heavy Duty Diesel Particulate: Emission Factors
Thomas Baincs
Joseph H. Somers
U.S. Environmental Protection Agency
Ann Arbor, Michigan
For Presentation at the '/1st Annual Meeting of the-
Air Pollution Control Association
Houston, Texas June 25 -30, "1973
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NOTK TO EDITORS
Under the new federal copyright law,
publication rights to this paper are
retained by the authoi(s).
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1. Background
One of Lhc operating characlcriitics of diesel engines is their emission
of particulate matter, part of which can be seen as visible smoke wlnle
the remainder is invisible. At temperatures, above about 260°C (500°!-),
it is believed(J) that the particulate is principally made up of small
agglomerated chains (about 1 micron long) of very small spheres of ele-
mental carbon (soot). At temperatures below abouL 260°C, these chains
are frequently coated with condensed material mostly in the form of high
molecular weight organic compounds, unburned hydrocarbons, some sulfur
dioxide, sulfates, and polynuclear aromatic hydrocarbons (PNA).
EPA has studied particulate emissions from diesel engines for the last
several years. The first such interest was in studying the visible
smoke component of particulate which was followed by TNA studies of
diesel exhaust. At about the same time as sulfate particulate emissions
from gasoline vehicles were beginning to be studied 0973), EPA started
measuring total particulate froni heavy duLy diesel engines. Smco this
time, interest in diesel particulate emissions has greatly increased,
which has in part been due to preliminary results indicating the potentia
carcinogenic nature of portions of the soluble organics from diesel
particulate. Also, the Clean Air Act As Amended August 1977 includes a
requirement for a motor vehicle particulate standard effective with the
1981 model year(2)*, thereby greatly increasing interest in particulate
emissions characterization.
2. Experimental Procedures
The fundamental objective in particulate sampling to date has been to
obtain a sample that is as close as possible to actual atmospheric
particulate. As such, the exhaust and attendant particulate is quenched
to temperatures of 52°C (125°F) or less at the sampling point. This is
consistent with the currently accepted definition of mobile source
particulate being anything that is collected on a specified filtering
medium tliat is maintained at or below 52°C, excluding condensed water.
The sampling temperature of 52°C has been selected as an appropriate
sampling point temperature for research purposes.
The methods that have been used to meet the sampling objectives for
heavy duty diesel engines have, in part, been adapted from technology
that was developed for light duty gasoline vehicle particulate sampling.
This involves the use of a dilution tunnel wherein engine exhaust is
mixed with dilution air and a sample of the mixture is filtered for
particulate emission rate determination. The major adaptation for heavy
duty diesels has been the use of an exhaust flow splilLer which is
ncccssaiy bccaus^ the large volumes of e>haust flow (in some engines, in
excess of 0.47 m /s or 1000 cfm) would require extremely large tunnel
* Numbers in parenthesis represent References found m back of paper.
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78-54.3
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flow capacity (7.0 m /s or 15,000 cfm) to dilute the exhaust to SP.'C.
Such large tunnel Hows would requite extremely large blowers (with a
very high initial capital equipment, cost) and it would ho difficult Lo
measure such large flows accurately. Therefore, the research work in
heavy duLy diesel particulate has, to date, been done with an exhaust
splitter thus permitting lower, somewhat more easily measured tunnel
flows as well as permitting the use of available CVS equipment.
In the exhaust splitter system, the engine-out exhaust is introduced into
a commercially-available muffler (of a type normally used with the
engine being tested), which contains two perforated tubes. One of these
tubes exits the muffler and leads to waste, and the other Lube goes to the
dilution tunnel. The Lubes are identical in perforations and length but
are different in outlet dianeter. fhe objective m building the splitter
is to give exhaust components an equal probability of exiting by the
diluLion Lunncl line or the wasLe line. In the research performed to
date, each engine is tested with a specifically tailored splitter so that
the resulLant flow to the dilution tunnel is sufficient to obLam an
adequate sample yet not so much as to result in excess temperatures at
the filter face. Some control is exerted over flow from the splitter to
the dilution tunnel by restricting the flow to waste.(3)
There are various types of filter media upon which diesel particulate
samples have been collected. With any filter, including glass fiber,
there exists the possibility of artifact formation from chemica] reac-
tions occurring on the filler during collection. This could be a problem
if the collected material were to be analyzed chemically, but when
particulate mass is the principal measurement to be made, the normal
proceduie has been to use hi mm glass fiber filters due to their good
particulate collection efficiency and their relatively low tendency
toward filter plugging.
In the EPA work at Southwest Research Institute, particulate mass emis-
sion rates have also been computed from the hi mm PTFE (polytetraCluoro-
ethylene, known as Teflon and made into filters with a trade name of
Fluoropore) filters. PTFE filters are used when sulfate emissions are to
be measured, because unlike glass fiber filters, the PTFE filters have a
low, relatively constant background sulfate level. However, they clog
easily and therefore are not usually the filter of choice for particulate
mass emissions sampling. A third source of particulate emission data for
dicsels comes from 20.3 cm by 25.4 cm (8 x 10 in.) glass fiber filters
through which higher flow rates are pulled so that sufficient sample is
obtainpd for PNA and other organic compound analyses However, results
indicate lhaL the particulate emissions results are pnrLially a function
of the filtering medium and filtering system employed. (3) This is due to
factors such as different filter retention characteristics and different
wall effects of various systems. Therefore, it is important to specify
what type of filter medium and system have been used to obtain particulate
emission results. All data repoiLcd in this paper were derived from
samples collected on 47 mm glass fiber filters.
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78-54.3
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A study was recently performed for EPA(4) wherein 54 filter media were
evaluated as to rhe appropi iaLeness of their use for collecting p.nticu-
late matter in auLon'obile exhausL. The parameters measured in Lhe ^Ludy
included aerosol collection efficiency, flow resistance, face velocity,
filter density, water and organic vapor sorption, manufacturing uni-
formity, fiber blow-off, filter loading and exposure to exhaust gases.
The results of this study indicated that one of the optimum filter media
was the Teflon-on-fiber glass filter (Pallflex Products Corporation is
one manufacturer of filter media of this type). It is likely that EPA
will ba using filter media of this type in Lhe future.
During Lhe course of CPA's heavy duty diesel parLiculate characterization
work, the resultanL particulate emissions data has been reported in
several units, including fuel specific (grams particulate per kilogram of
fuel, g/kg fuel) and work specific (grams particulate per kilowatt hour,
g/kw hr). It seems that each unit has both strong advantages as well as
certain disadvantages. The work specific units seem particularly well
suited for use in regulating particulate emissions. This was also the
conclusion reached when units were being considered for gaseous emissions
regulation.(5)
The work specific units have two disadvantages. The first is that, in
the steady state modal weighting procedure, the composite weighted emis-
sion number has a slight high bias in that the significant idle particulate
emissions are not offset by a finite power output. The other disadvantage
is that it is very difficult to compute a meaningful overall emission
factor* from a work specific number.
These disadvantages are overcome by using fuel specific units. The fuel
specific units take into full account the idle mode emissions as there is
fuel flow at idle. Also, these units are much more meaningful in computing
particulate emission factors as there is quite a bit of fuel usage data
available, both on a gross scale and individual vehicle scale. The two
units are very closely related by the work specific fuel consumption
which is relatively constant over a wide range of engines. The major
disadvantage of using these units from a regulations point of view is
that they would tend to give a certain amount of advantage to less
efficient engines. At this time it has not been decided which units EPA
will use for regulation of heavy duty particulate. It is possible that
EPA may regulate particulate emissions on the basis of work specific
units but may require reporting 111 both these units as well as fuel
specific units.
* The term "emission facLor" is used to indicate an emission rate
in terms of mass per distance traveled.
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The particulate data that has been gathered to date lias been based on
the 13 steady state operating modes of Lhe Federal Test Procedurc((>).
The method for computation of composite emissions fiom tins type of
modal data was staled by Bascon et al ..(5), but the derivation of Lhut
method was not. The derivation which follows(7) was used for reducing
the modal data which is reported in this paper.
Notation:
i = mode number
= time-based weighting factor
= (timc)1/S(time)]
= mode fuel rate, kg/hr
Pj = mode power, kW
Plx = mode paiticulate rate, g/hr
DERIVATION 1 - Grams per hour units
Cycle pollutant = h
emissions (g/hr) gh'
p D grams pollutant /"cycle
gh enicted during evele/ time, hours, or
P „ " PH^Utan^ /1, (time) ..
gh 1 \ produced In tsodg / 1 i
Using the above notation,
P . = J\Pt (tine),/I, (time),,
gh 1 1 11 1
and substituting gives
DERIVATION 2 - Work specific units
Cycle pollutant = p where
emissions (g/kW hr) gkh*
P = grams pollutant /work performed
gKh emitted during cycle/ during cycle, or
using the above notation
pgkh ¦ zi PtiCt^e)1/!;iP1(tiJne)i.
Dividing Lhe numerator and denominator
by total cycle time yields,
j, rtj (tiine)(/i"^ (1 ins)
Ekh
i?i(timc)1/l.i(tin;e)i
which, upon suDSitution, reduces to
P , . - I Pc.U./E.P.W .
pVh l 1 i 1 1 l
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DPRIVATION 3 - Fuel specific units
Cvcle pollutant =
emissions (g/Vg fuel) gkf
p r fratns r^Hutant /kg fuel consumed
gkf emitted du-ing c>cle/ over cycle, or
using the above notation
PgVf " Vi(timeVWtine)i-
Dividing the numerator and denominator
by total cycle Litre yields,
PgM ¦= EPt1graiii{10) therein seveial types of fuels have
been run to note the eEfcct of the fuel on the emissions from the two
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78-54.3
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engines. The fuels used were 1) No. 2 Diesel fuel (DF//2) enussion Lest
fuel, 2) DF:,'2 which clobely approximates a "national average" fuel,
3) DFj/1, 4) DF,;2, "mininiurn" quality, which has a low (.etane (abouL 42)
and is high in aromalics, and 5) Dlv2, "prenium" quality, which lias a
high cetanc (abouL 52) and is high in paraffins.
Engines 3 and 7 were run in a program(8) that characterized the emis-
sions from these engines under two different configurations each. The
Detroit Diesel Allison Division (DDAD) 6V-71 engine was operaLed with
both Low Sac Needle size 60 (LSN-6) fuel injectors and B-6QE injectors.
The B-60E injectors are needle type with a constant end of injection
helix instead of a constant start of injection helix. The Cummins 855
TC four-stiokc engine was operated m a "current" configuration where
the engmo used standard Static injection timing and in a "low" emis-
sions configuration where variable injection Liming was employed.
Engine nu.uber U (DDAD 8V-?1TA, two-stroke) was run iu the same progran
but in just one configuration which represented the production engine.
Engines number 3 and 4 were operated on commercially available BF1 and
engine number 7 was run on a DFi/2 with nominally "national average"
charactenstics.
Table I
Table of Fuel Specific Particulate Enission
Rates for Two-Stroke Heavy Duty Diesel Engines
Engine
Test
Test
Particulate Et-!s
si cms p/kc Fuel
Nacbcr
Etiqi-ie
Fuel
Conditions
Ter,t Result
(. 1 i from >'c in
1
6L-71T
DF1
Koraal
3.8
0.71
1
61-71T
Drl
Ignition accelerator
additive used ir. fuel
3.7
0.78
1
6L-71T
0F2
Normal
3.7
0.78
1
6L-71T
DF2
Emc'^e suppress a it used
In fuel
4.6*
0.11
1
6L-71T
DF"1.5"**
TJormal
3.i
1.C0
1
6L-71T
DF"1.5"**
STocke suppress an1, used
in fyel
3.7
0.78
2
St'- n
OF2 Emissions
1
6.13
1.0?
i.
6V-71
Dr: flat. Avg.
N c rc„ 11
6.61
1.39
2
6V-71
cn
-ionr.al
5.69
0.71
2
6V-71
DF2 Mm. Ql.i1
J-orauii
5.89
0.86
2
6V-71
DF2 Pr^-ii.-r
f!jrir.al
5.52
1.33
3
6V-71
Drl
LS:i 60 Injectors
4.43
0.23
3
6V-71
DF1
B 60C Injectors
5.75
0.75
A
8V-711A
cr2
Noiral
2.45
1.71
Averjg.?
4. 74
Sta.iJard Deviation (d)
1.34
* Data
corrected
fcr ^rieccor mil
Jur.ction error via personal c^Tjiiinicacien
with
authors.
** A DT vith properties ijctueou 2?
and i)F' 1
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7S-54.3
Table II
Table of Fuel Specific Particulate Erussion
RaLes £or four-Stroke Heavy Duty Diesel Engines
En sine
Test
Test
Particulate-
Nimber
Engine
Fuel
CondiLions
lest Result
5
855 TC
on
Notnal
1.0
5
855 TC
DF1
Injection accelerator
aaditive used In fuel
0.95
5
855 TC
DF2
Normal
K6
5
855 TC
DF2
Smoke suppressant used
in fuel
2.0
5
B55 TC
DF"1.5"**
Normal
1.2
5
855 TC
S^ofcc suppressant used
in fuel
1.3
6
3J08
DF2 Emissions
Konnal
3.11
6
320S
DF2 N.it. Avg.
Kormal
3-09
6
320S
DF1
Normal
1.B2
6
3208
DF2 Man. Qual.
Koirsal
3.36
6
3208
DF2 Premium
Morioal
2.04
7
835 TC
DF2
"Fixed" Timing
1.44
7
&55 TC
DF2
"Variable" Timing
2.09
8
ETAY(B)
673A DH
Wornal
3.53
9
3208 (ECR) DF2
Hormal
10.16
All engines
Average
2.54
Standard Deviation (o) 2.27
All engines, except 59
Average 2.10
Standard deviation(a) 0.96
@ The "all engines" mean and standard deviation
** A DF with properties between DF#2 and DF01
n's from Mean@
0.73
0,75
0.47
0.29
0.64
*
0.60
0.20
0.19
0 36
0.31
0.12
0 54
0.25
0.52
3.30
Engines 8 (Mack. ETAY(B) 673A, four-stroke) and 9 (Caterpiller 3208 EGR,*
four-stroke) were tested m a progrnm(ll) that is currently in progress.
Both engines wore tested in production configurations with DF//2. Engine
number 9 is noteworLhy as it is the only test engine to have EGR.
The data are presented m two groups, Lhe four-stroke and two-stroke
engines. This is because the data developed to date indicate that the
two-stroke engines Lend to emit almost twice the parLiculaLe as the
four-stroke engines (with the exception of the 4-stroke tGR engine,
which emitted almost A Li^es Lhe particuljte as Lite average non-EGR 4-
Etrokc engine). Since Lhe objective is to establish a particulate
emission i-aLe that as. representative of actual conditions, all data in
each of these two groups are averaged together with no spe-cial statistical
consideration given to the individual results. This is felt lo be
justified as trosl test fuels and conditions. Crin :jc expected Lo be encountered
in actual use. Those tests run under somewhat non-actual use conditions
* Txhaust Gas Rocncula Lion
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78-54. 3
(e.g. DF1 or 1.5 in a 4-stroke) yielded results that varied from the
mean by one standard deviation or less. Therefore, in general the
averaged results are considered Lo be representative of actual use.
All ot the data presented represent particulate emission rates computed
from 47 mm glass fiber filter analysis results. Also, all of the data
ls relatable to 13 mode data. However, all of the data may not have
been computed from tests in which 13 discrete filters '.'ere taken. Some
data come from 7 mode tests which used distributed weighting factors
similar to 13 mode weighting factors to arrive at a composite parti-
culate emission rate.
In order to compute a meaningful heavy duty diesel particulate emission
factor, several types of data are required. These include 1) fuel
specific particulate emission rates for heavy duty diesel vehicles, 2)
heavy duLy diespl average speed data, and 3) heavy duty diesel fuel
usage data. All of tins data should be representative of actual use
conditions. Much, but not all, of this data is currently available.
The first type of data required is the m-use fuel specific particulate
emission rate. The available data has been presented in Tables I and
II. However, this data is representative only of a few select number of
engines operated at steady state modes under laboratory conditions.
Therefore, the data is not necessarily representative of actual m-usc
particulate emission rates.
EPA is currently initiating a program to study particulate emission
rates of heavy duty diesel engines operated over transient cycles. This
should significantly improve the estimates of in-use particulate emis-
sions. It is expected that transient operation will yield higher parti-
culate emission rates.
For the purposes of this analysis, the data presented in Tables I and II
will be used with only one minor change. The four-stroke emission
factor that wil] be used will be the one excluding the EGR engine (2.10
g/kg fuel). This is because the EGR engine represents only about 14%
of current engines sold(.12) and a much lower percent of the total heavy
duty diesel engine population. By eliminating the result from that
engine, the particulate emission factor becomes more representative of
results from steady state, laboratory Lests of the general heavy duty
diesel population.
The second type of data required for a meaningful heaw duty diesel
engine factor is average speeds for actual heavy duty diesel vehicle
usage. Data of this type was developed by the Coordinating Research
Council CAPE-21 project whetein trucks and buses were instrumented and
operated in typical use in Los Angeles and New York City. Tour buses
were used for data accumulation in each city as well as 17 diesel trucks
in los Angeles and 14 diesel trucks in New York City. The data thus
obtained was reduced by an EPA contractor(13) and is presented in Table III.
These average speed data will be used for selecting the fuel economy
values used in computing the particulate emission factors. The data
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78-54.3
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Crow the two cities can be considered tu represent extremes of urhau
heavy duLy vehicle usage, with usage in oLlier cities falling soinewlieic
in between these values.
Tabic III
Average Vehicle Speeds for Heavy Duty Diesel
Vehicles Under Various Types of Usage
Average Speed (km/hr)
City
Usage Type
Diesel Trucks
City Buses
Los Angeles
Non-Freeway
25.6
26.8
Freeway
74.9
73.3
Combined
49.6
31.9
New Yoik
Non-Freeway
14.4
12.5
Freeway
43.6
34.5
Combined
20. 7
12.7
The third type of data required is fuel usage data for heavy duty diescl
vehicles. Such daLa comes from a study(lA) wtierein emissions and fuel
consumption data were gathered from a wide vaneLy of heavy duty vehicles
under several types of duty cycles tested on chassis dynamometers.
Among the vehicles tested were twelve diesel trucks (eight equipped with
4-stroke engines and four with 2-stroke engines) and two city buses,
both with 2-stroke engines (the typical bus engines). The duty cycles
over which the trucks were tested included eight steady state speeds (0,
5, 10, 15, 20, 30, 40 and 35 mph), four driving cycles (average speeds
of 5, 10, 15 and 20 mph) and three sinusoidal driving schedules (20 + 5,
30+5 and 40+2 mph). The buses were operaled over duty cycles that
included seven steady states (0, 5, 10, 15, 20, 30 and 40 raph), four
driving cycles (5, 10, 15 and 20 mph average speed) and two sinusoidal
driving schedules {20 + 5 and 30+5 mph). The data was obtained under
laboratory conditions and does not represent on-road fuel consumption
which could be higher. All of the vehicles were tested with dynamometer
inertia weights corresponding to the vehicle fully loaded, half loaded
and empty.
The fuel consumntion': developed m this study arc for a series of quite
uniformly spaced speed points whereas Lhe vehicle usage average speeds
(Tabic III) are at intermediate points. Therefore, simple linear inter-
polation was used to determine the fuel consumption values Tor trucks
(and engines) and buses for the vehicle usage average speeds. Tnu
results of these calculations arc presented in Table IV.
With the fuel consumption values thus determined, Lhe particulate emis-
sion factors can be computed from the following formula:
Part. Emission _ /partlcll]_ate emissions) (fuel conversion) (fuel consumption)
Iactor (g/km) r
= (g part./kg fuel)(0.851 kg fuel/litre fuel)(]iLre fuel/100 km)
(1/100)
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78-54.3
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The rcsulLs of these calculJLionf. are presented, in Table V. This table
should be consulted Cor specific emission factor numbers as an overall
heavy dutv diesel particulate emission factor number is loss meaningful.
However, if a condensation must be made, it can be partially done on the
basis of vehicle sales(L2). About 1.78 percent of the heavy duty vehicles
sold in 1975 were buses. Of the remaining 98.22% (trucks), 23.44% were
2-st.ioke (all of the Detroit Diesel e.ngmes, the only mauufactusrer of 2-
stroke) for a weighting factor of 23.02%. The 4-stroke engines reure-
sent 76.56% of the trucks for a weighting factor of 75.20%. Using these
weighting factors on the half load, combined usage emission factors
yields a weighted New York City usage emission factor of 1.31 g/kra and a
Los Angeles usage emission factor of 0.83 g/kra. Therefore, the heavy
duty vehicle particulate emission factor for half loaded vehicles operating
in urban areas (combination of both freeway and non-freeway use) is
between 0.84 and 1.31 g/km, depending on the average speed of use. This
figure assumes no engine malfunction, is based on steady state, labora-
tory emission results and uses laboratory fuel consumption values.
It must be emphasized that the most accurate emission factor for heivy
duty vehicles is obtained by using Table V. This is especially important
when the vehicle mii. deviates from the mix used to compute the weighting
factors. Tor example, it is conceivable that, in a downtown area where
trucks are prohibited from the streets and the only heavy duty diesel
vehicles are buses, the emission factor would be between 1.84 and
2.66 g/kra (half loaded buses, combined usage) which is significantly
higher than the above-mentioned composite emission facLor.
Table IV
Table of Fuel Consumption Values
Used in Computing Particulate Emission Factors
Vehicles,
Engines,
Loads
Trucks
2-Stroke
Empty Load
Half Load
Full Load
4-Stroke
Bu^es
Average Fuel Ccmsunpticin (t/100 km)**
Les Angeles
New York City
Non-
Frecwav Frecuav Combined
(14.4)* (43.6) (2C.7)
Non-
Frecvjay Freeway Combined
(25.6) (74.9) (-19.6)
55.2
60. 3
70.0
32.3
36.4
46.4
48.4
55.7
65.7
45.0
52.4
63.4
35.9
42.1
48.5
* hui-jbers In parentheses represent average speed (kc/hr) at
the three usage conditions tor the two cjtias. These
numbers come I roa TaMc 111.
¦-* Based on data collected under laboratory conditions,
on-rond fuel consumption nnv be higher.
30.7
36.1
42.5
Empty Load
52.8
33.0
46.0
42.9
32.4
30.7
Half Load
60.9
37.6
54.6
51.7
37.5
34.9
Full Load
69.0
44.3
63. 9
60.8
43.0
40.-8
(12-5)
(3i.5)
(12.7)
(26.8)
(73.3)
(31.9)
Emp ty Load
64.3
43.9
63. 9
48.4
35.6
45.3
Half Load
66.5
44.6
65.9
47.6
41.6
45.5
Full Load
73.5
49.6
73.1
53.5
47.7
50.8
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78-54.3
13
Table V
Tabic of lleavv DuLy Diesel
Vehicle rarticuJace Knisslou Factors
Paniculate Emission Factor;. (c/lun) **
Vehicles,
Nerf Yoik City
I S^PO
Los
A:.r ules
Usase
Engines,
Non-
Non-
Loads
Freewav
Freeway
CoTnbi ned
Freewav
Freevav
Coirbi ned
Trucks
(14.4)*-
(43.6)
(20. 7)
(25.6)
(74.9)
(49.6)
2-Strokc
Empty Load
2.2
1.3
2.0 ^
1.8
1.5
1.2
KalC Load
2.4
1.6
2.2 1
2.1
1.7
1-5 /
Full Load
2.8
1.9
2.7
2.6
2.0
1.7
4-Sltrokc
EinpLy Load
] 0
0.6
0.8
0.8
0.6
0.6
Half Load
1.1
0.7
1.0
0.9
0.7
0.6
Full Load
1.2
0.8
1. 2
1.1
0.B
0.7
Buses
<12. 5)
(34.5)
(12,7)
(26.8)
(73.3)
(31.9)
Erapty Load
2.6
1.8
2,6
2.0
1.4
1.8
rialf Load
2.7
1.8
2, 7 f ^
1.9
1.7
1.8 Z
Full Load
3.0
2.0
3.0
2. 2
1.9
2.1
* Numbers in parentheses represent average speed (km/hr)
at the three i.bage conditions Ear the cities
These nunbers come from Table III.
** Based on data co)lected under laboratory conditions,
on-road emission factors may differ.
There have been other studies of Diesel particulate emissions, but
results of such studies can't be compared directly with the emission
factors in Table V because those studies address particulate emissions
only in terms of mass per volume exhaust, mass per time, mass per fuel
used, or mass per work output, rather than mass per distance traveled.
However, a comparison of the fuel specific emission rates in Tables I
and II with corresponding results from some oLher studies (3, 15, 36)
indicates that the range of engines and operating conditions used
in this study is wide enough to be representative of other sLudics.
The emission of particulate from heavv duty diosel vehicles yields some
interesting figures from a national emission inventory point of view.
Such on inventory has been computed from fuel consumption figures(18)
shown in Table VI. The truck emissjors were computed assuming that 23%
of the trucks are 2-stroke and the remainder 4-stroke. All of the buses
are assumed to be 2-stroke. One of tne more important sources of urban
particulate emissions are the local buses, which, according to the
computations, emit 5570 metric tons of particulate per year in urban
areas. To this urban particulate emission rate must, be added the
component attributable to trucks and, Lo a lesser degiee, intercity
buses.
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78-54.3
14
1.ible VT
"kil)Jc of Diesel i vie] Co Ms u"i,i 11 on and Pir t i rul.ilo rr:i>, ..ms
for Ituee o. I'uivn Duly LHe-.eJ "c'u^lo"!
1975 Fuel l'arLicu] ale
Emission ConsumpLion [.missions
Source (rnlliou barrels) (ineinc Loiis/vc.ir)
Trucks, diescl 216.2B 79,850
Inlercity bjses 4.29 2,750
Local buses, diesel 8.69 5,570
TOTAL 229.26 88,170
4. Conclusions
A. Cased on tests done for EPA by Southwest Research Institute, the
average particulate results from steady state laboratory tests for
2-stroke engines is 4.74 g/kg fuel and for 4-strokc engines is
2.64 g/kg fuel.
B. The emission factor range for urban areas which permit only local
buses is from 1.8 to 2.7 g/km (2.9 to 4.3 g/mi) of particulate.
This assumes all half load buses, combined usage (which is very
close to non-freeway usage), no engine malfunctions and on-road
fuel consumption equal to the laboratory fuel consumption, and is
based on steady state particulate test results.
C. Diesel trucks emit, on a nationwide scale, 80,000 metric tons of
particulate per year, intercity buses emit 2,800 metric tons
particulate/year and local buses emit 5,000 metric tons per year
for a total of 88,000 meLric tons of particulate per year.
EPA is initiating a study of particulate emissions (and fuel economy)
under laboratory transient operating conditions. The transient cycle
will represent urban heavy duty vehicle use and will therefore yield
results that more accurately reflect such use.
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78-54.3
15
References
1. I.M. Khan, C.ll.T. Wang and B.H. Langridge, "Coagulation and
Combustion of Soot Particles in Diesel Engines", Combust ion
and Finnic, Vol. 17, No. 3, December 1971, pp. 409-419.
2. The Clean Air Act As Amended August 1977, Title II, Section 202(a)
(3) (A) (m)., Committee Print Serial No. 95-11, U.S. Government
Printing Office, November, 1977.
3. C. T. Hare, K. J. Springer and R. L. Bradow, "Fuel and additive
effects on diesel particulate-developmcnt and demonstration of
methodology", SAE Paper 760130, (1976).
4. ArLhur D. Little, Inc., "Evaluation of filter media for quantitative
collection of particulate matter from engine exhaust", Tjnal Report
to EPA/ORD/MSliRB from Contract Wo. 68-02-12, March 29, 1977.
5. R. C. Bascum, G. C. Hass, "A status report on the development of
the 1973 California diesel emissions standards," SAE Paper 700671,
(1970).
6. "Heavy-duty engines for 1979 and later model years - certification
and test procedures", Federal Register, Vol. 42, No. 174, September
8, 1977.
7. C. T. Hare, Southwest Research Institute, San Antonio, Texas,
private communication, 1977.
8. K. J. Springer, "Investigation of diesel-powered vehicle emissions
VII," EPA Report No. EPA-460/3-76-034, February, 1977.
9. C. T. Hare, "Methodology for determining fuel effects on diesel
particulate emissions," EPA Report No. EPA-650/2-75-056, March,
1975.
10. C. T. Hare, "Characterization of diesel gaseous and particulate
emissions," DrafL Final Report for EPA Contract No. 68-02-1777,
September, 1977.
11. K. J. Springer, "Characterization of sulfates, odor, smoke, POM and
particulate from light and heavy-duty engines," Progress Reports for
EPA Contract No. 68-03-2417, 1977-78.
12. Based on private communication with Mr. J. C. Hafele, Caterpillar
Tractor Company (3/31/78), and information from Reference (15).
13. C. J. France, "Category selection for transient heavy-duty chassis
and engine cycles," Draft Technical Support Report For Regulatory Action,
F.PA/0MS"\PC/LCTD, April, 1978.
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7S-54.3
J 6
14. C. M. Urban, K J. Springer, "Study of emissions from heavy-duty
velucles," EPA Report EPA-460/3-76-012, May, 1976.
15. Motor Vehicle Manufacturers Association of the U S., Inc., Detroit,
Mi, "Factory truck sales," February 9, 1976.
16. C.T. Vuk, M.A. Jones, J.H. Johnson, "The Measurement and Analysis
of Lhe Physical Character of Diesel Particulate Emissions", SAL' Paper
760131, (1976).
17. L.E. Frisch, J.11. Johnson,, D.G. Leddy, "Effect of Fuels and Dilution
Ratio on Diesel Particulate Emissions", Draft report Eor presentation
at February 1979 SAC Congress.
18. D. B. Shonka, A. S. Loebl, P. D. Patterson, "Transportation enei gy
conseivation data book Edition 2," Oakridpe National Laboratoiy
Report ORNL-5320, Octobei, 1977.
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