TECHNICAL REPORT

Evaluation of Exhaust Emissions
Data for Diesel Engines used in

Underground Mines

US DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service

Center for Disease Control

National Institute for Occupational Safety and Health

 

any"

EVALUATION OF EXHAUST EMISSION§ DATA FOR
ESEL ENGINES USED IN UNDERGROUND MINES

John N. Sheehy, P.E.
Division of Physicai Sciences and Engineering

DOCUMEWS DL:‘:—=.;£TIIILI‘;I
I71" ‘ I“
‘1“..:,,.l UT \»- L
____ _.

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
PubTic HeaTth Service
Center for Disease ControT

Nationai Institute for OccupationaT Safety and Heaitnfi'

4676 Columbia Parkway
Cincinnati, Ohio 45226

September 1980

XDB1
1552
PGBL

éL/L‘77974/
Pufib

DISCLAIMER

Mention of company names or products does not constitute endorsement by the
Nationa] Institute for Occupationa] Safety and Health.

DHHS (NIOSH) Publication No. 80-146

ii

ABSTRACT

This report presents an evaluation by the National Institute for Occupational
Safety and Health of exhaust emissions data for diesel engines used in under—
ground mines in the United States. The data were collected by the Mine En-
forcement and Safety Administration (MESA) during the period of l974 through
l977. (MESA became the Mine Safety and Health Administration (MSHA) on March
9, l978). Diesel exhaust pollutants evaluated were nitrogen oxide (NO), car-
bon monoxide (CO), and carbon dioxide (C02). The pollutants were collected
from 4—, 6—, 8-, and lZ-cylinder indirect injection engines prior to instal—
lation of any emission control device.

Findings include: N0 emissions were higher from turbocharged aftercooled en—
gines than from naturally aspirated engines. C0 emissions were considerably
less from turbocharged aftercooled engines than from naturally aspirated en-
gines. N0 emissions (gm/bhphr) averaged over modes 3, 6, 9, and 10 of the En-
vironmental Protection Agency (EPA) l3-mode cycle were higher than NO levels
at peak torque or at rated load/speed.

Since exhaust emission levels varied among diesel engines that were alike as
to fuel injection system, air intake system, and numbers of cylinders, the use

of several makes and models of engines is recommended when testing the effec-
tiveness of emission control devices.

U.S. DEPOSITORY

DEC 021980

-118(Nfl

 

CONTENTS
Abstract .................................. iii
Acknowledgments .............................. vii
Introduction ........................ I ........ 1
The Use of 0iese1 Engines in Underground Mines ................ 3
Diese1 Engine Combustion Systems and Exhaust Emissions ............ 4
Study Methodo1ogy for the Ana1ysis of MSHA Diese1 Exhaust Emissions Data . . .7
Eva1uation of Diese1 Exhaust Emissions .................... 9
Conc1usions ................................. 32
Recommendations ............................... 33
References ................................. 34
Appendix: Diese1 Engine Test Data ..................... 37
FIGURES
1. N0 Emissions Map in gm/hr ........................ 5
2. N0 Emissions versus Speed and Load (13-mode cyc1e) ........... 13
3. N0 Emissions versus Speed and Load (NA engine) ............. 14
4. N0 Emissions versus Speed and Load (TA engine) ............. 15
5. C0 Emissions versus Speed and Load (13-mode cyc1e) ........... 16
6. C0 Emissions versus Speed and Load (NA engine) ............. 17
7. N0 Emissions (gm/bhphr) versus F/A Ratio ................ 18
8. N0 Emissions (gm/hr) versus F/A Ratio ................. 19
9. N0 Emissions (gm/hr) versus F/A Ratio and Engine Speed ......... 20
10. C0 Emissions (gm/bhphr) versus F/A Ratio ................ 21
11. C0 Emissions (gm/hr) versus F/A Ratio ................. 22
12. Horsepower versus F/A Ratio ...................... 23
13. Horsepower versus F/A Ratio and Engine Speed .............. 24
14. Horsepower versus Fue1 Rate (at 2,000 rpm) ............... 25
15. N0 Emissions versus Horsepower (at 2,000 rpm) ............. 26
16. CO Emissions versus Horsepower (at 2,000 rpm) ............. 27
17. N0 Emissions versus Horsepower With and Without CH4 Atmosphere ..... 28
18. C0 Emissions versus Horsepower With and Without CH4 Atmosphere ..... 29
19. N0 Emissions versus Load and Humidity ................. 31
TABLLES
1. Test Conditions of Humidity, Temperature, and Pressure ......... 8
2. Diese1 Engine Exhaust Emissions ..................... 9
3. Diese1 Exhaust N0 Emissions (gm/bhphr) ................. 11
4. Diese1 Exhaust N0 Emissions (gm/hr) .................. 12
5. N0 Emissions Uncorrected and Corrected for Humidity .......... 30

ACKNOWLEDGMENTS

We are grateful to Messrs. Fred Sharp, Allen Nagel, and Steve Sawyer of the
Mine Safety and Health Administration (MSHA) for providing the diesel exhaust
emissions data used in this report.

We also wish to thank Mr. Joseph Burkart, Environmental Protection Agency; Mr.
Richard Holmquist, American Mining Congress; Mr. Allan Nagel, MSHA; and Mr.
William Crouse, National Institute for Occupational Safety and Health, who
provided technical guidance in the preparation of this manuscript. The
manuscript was patiently and very ably typed by Ruby Watson.

vii

INTRODUCTION

The use of diesel powered equipment in underground mines is of great concern
to the National Institute for Occupational Safety and Health (NIOSH), the Mine
Safety and Health Administration (MSHA), and the mining industry. NIOSH is
concerned about the possible health effects of diesel emissions, particularly
combined with other mine chemicals such as coal dust. NIOSH has examined the
health effects resulting from exposure to a combination of dust and diesel ex-
haust emissions in noncoal mines, and is currently studying the health effects
of diesel exhaust emissions in coal mines. There are serious concerns about
possible synergistic effects of respirable coal dust particles and diesel ex-
haust emissions.

In a letter of June 7, 1976, NIOSH advised MSHA against further introduction
of diesel powered equipment into underground coal mines until current health
studies on the effects of diesel emissions were completed.1

The mining industry has shown strong interest in the health aspects of diesel
powered equipment. The American Mining Congress (AMC), which represents the
industry, sponsored a study of the health effects of diesel exhaust emissions.
The study was performed by Environmental Health Associates (EHA) and included
an analysis of the Rockette Report, a study of coal mine mortality. In this
study, EHA stated that the United Mine Workers of American (UMWA) Denver Dis-
trict, "which accounts for 95 percent of all dieselized coal mines in the
United States, had the lowest risk oi death from all causes (SMR.80), all can-
cers (SMR.70), and cardiovascular disease (SMR.70)" and “the second lowest
risk of death (of all UMWA) for respiratory cancer (SMR.60), third lowest for
digestive cancer (SMR.73), and second highest for emphysema (SMR l.90)."2

Much more work needs to be done to determine the health risks of diesel powered
equipment in underground mines. Meanwhile, research is underway to control the
emissions from diesels. This report is a first step in a continuing effort to
control diesel exhaust emissions. This report presents and evaluates emissions
data for diesel engines used in underground mines in the United States. The
emissions data were collected by MSHA, formerly the MESA, at the MSHA Testing
and Certification Center in Bruceton, Pennsylvania. The data were collected
during the period l974 through l977. MSHA uses the data in certifying engines
for use in underground mines and in determining mine ventilation requirements
for various types of diesel engines.

The MSHA data have been evaluated by the NIOSH Control Technology Research
Branch. The data include the following pollutants: nitrogen oxide (NO), car-
bon monoxide (CO), and carbon dioxide (C02). Exhaust emissions in the tail-
pipe were collected prior to installation of any emission control devices.
Diesel exhaust emissions following the installation of control devices are not
discussed in this report.

This report examines only indirect injection (prechamber) combustion diesel
engines (101). This is logical since it was pointed out in the NIOSH/Morgan-
town Diesel Workshop in September l977, that 101 diesel engines produced lower

NO, C03 and hydrocarbon (HC) emissions compared to direct injection diesel en-
gines.

THE USE OF DIESEL ENGINES IN UNDERGROUND MINES

Diesel powered equipment has found use in underground mines because of its mo-
bility, high thermal efficiency, and potential for low exhaust emissions. The
diesel engine is relatively clean if it is properly designed, adjusted, and
maintained. One of the major reasons diesel engines are used in mines is the
low volatility of diesel fuel.4a5,6

Other advantages of the diesel are: (1) rapid refueling; (2) long periods be-
tween refueling; (3) high specific energy storage of fuel, i.e., a lot of en-
ergy (diesel fuels) can be stored in a small volume; (4) numerous power lev-
els; and (5) the possibility of various methods of power transmission.

Some disadvantages of diesels used underground are: (l) exhaust emissions; (2)
high ventilation needed to cool and clean air; (3) hot engine surface; (4)
flameproofing required in gassy mines; and (5) noise.

The primary type of diesel powered equipment used in underground mines are
load haul-dump vehicles (LHD), front-end loaders, jumbo drills, roof drills,
diesel shuttle trucks, supply vehicles, personnel cars, and small jeegs. Power
outputs for most diesels underground range from 60 to 200 horsepower. ,9,IO

Underground mines employing diesel engines fall into two broad categories:
noncoal mines and gassy noncoal mines. Diesel engines are certified for use
in noncoal mines by MSHA under Title 3l, Part 32, of the Federal Register,
Schedule 24. This regulation states, “the exhaust gas, after dilution with
air, shall contain no more than 0.5-percent by volume of carbon dioxide, lOO
ppm by volume of carbon monoxide, and 25 ppm by volume of oxides of nitrogen
(as equivalent N02)" and "within the rated power output range, the undiluted
exhaust gas of the engine shall contain not more than 0.25-percent by volume
of carbon monoxide."1

Diesels used in the second type of mine (gassy noncoal mine) are regulated
under Title 30, Part 36 of the Federal Register, Schedule 3l. (The tenn non—
coal mine is a misnomer since diesel engines tested under Schedule 31 are used
in coal mines as well as gassy noncoal mines. MSHA might consider a different
term than "gassy noncoal mines" when referring to Schedule 3l-type mines.)
Schedule 3l requires that "the concentration of exhaust gases diluted by air
shall not exceed 0.25-percent by volume of carbon dioxide, 50 ppm by volume of
carbon monoxide, and l2.5 ppm by volume of oxides of nitrogen (as equivalent
N02)" and "the undiluted exhaust gas shall contain not more than 0.30—per-
cent by volume of carbon monoxide, and 0.20-percent by volume of oxides of
nitrogen (as equivalent N02) under any conditions of engine operation when
the intake air inixture contains l.5 -+ 0.l percent by volume of Pittsburgh
natural gas."12 British regulations require that diesel locomotives used in
underground mines emit no more than 0.2-percent by volume of carbon monoxide
and 0.l-percent by volume of oxides of nitrogen.

3

DIESEL ENGINE COMBUSTION SYSTEMS AND EXHAUST EMISSIONS
DIESEL COMBUSTION

The diesel engine air, which is neither throttled nor restricted, is pulled
into the engine cylinders which compress the air. Then diesel fuel under high
pressure is injected and the air/fuel mixture ignites spontaneously in the high
temperature/pressure conditions in the cylinder. With the diesel engine, the
power output is dependent only on fuel rate.4

The diesel engine differs greatly from the spark ignition (SI) gasoline engine
where the fuel-to-air mixture is fired by a spark plug. Furthermore, the SI
engini output depends not only on fuel rate. but also on the amount of air in—
take.

There are two basic diesel combustion systems: the direct injection and the
indirect injection or prechamber engine. In the direct injection engine, fuel
is injected directly into the main chamber or cylinder through orifices. The
fuel mixes with the air in the cylinder, vaporizes, and burns. With the in-
direct injection engine, fuel and a small amount of air, enters the prechamber
and begins to burn. This air/fuel mixture then enters the main chamber where
combustion is completed.4

Diesel engines that take ambient air into the combustion zone are called nat-
urally aspirated. There are both direct injection and indirect injection nat-
urally aspirated engines. The amount of air to the diesel engine can be in-
creased by the use of a turbocharger, which consists of an exhaust-driven
turbine in turn driving a compressor. The turbocharger forces a greater amount
of air into the system and allows increased power output for the same size
engine. Because of the additional heat generated from a turbocharged engine,
an aftercooler may have to be added to dissipate the heat.4

DIESEL EXHAUST EMISSIONS

Diesel engines produce approximately 200 cubic feet of exhaust from l pound of
fuel. Exhaust emissions are primarily C02, CO, NOX, water vapor, and free
nitrogen. Other exhaust pollutants include HC, particulates, $02 and odor.
The C02 produced is directly proportional to the amount of fuel burned in the

diesel engine and cannot be reduced by emission control devices. Therefore,
ventilation is the only way to lower C02 emissions to acceptable levels in
mines. CO, HC, odor, and N0x from diesel engines can be reduced through the
use of control devices. C0, HC, and odor are reduced by catalytic converters
and fuel injection refinements. C0 emissions also can be reduced by derating
diesel engines. N0X can be reduced by exhaust gas recirculation (EGR), fuel
injection modification (including retarded timing and increased fuel rate), and
water injection. Particulates are controlled by turbocharging, power limita-

4

tion, and a catalytic scrubber/water scrubber combination. Proper maintenance
is also critical in controlling particulates.

$02 in the exhaust is proportional to the sulfur content of the fuel, and

thus is controlled by minimizing the amount of sulfur in the fuel.4a5a 0,14,15
The use of any spec1 1c control technique for reduc1ng one pollutant can result

in the increase of other pollutants. For example, EGR reduces NOx emissions,
but increases C0 and unburnt hydrocarbons.

Measurement of diesel exhaust emissions is normally performed in the labora-
tory using an engine dynomometer. The dynomometer controls engine speed and
loading. Fuel usage, airflow to the engine, and intake and exhaust tempera-
tures and pressures are also recorded. Techniques for measuring diesel exhaust
pollutants are found in the following publications: (l) Bascom, R. C. and

G. C. Hass, A Status Report on the Development of the l973 Diesel Engine Emis-
sions Standards, Nat. Soc. of Automotive Engrs., Los Angeles, August 24-27,
l970, SAE Paper 700671, l5 pp; and (2) Control of Air Pollution, from New
Motor Vehicles and New Vehicle Engines, Vol. 37, No. 22l, November l5, l972,
pp. 24250-320.l4

Upon collecting diesel emissions data for various speeds and loads, the emis-
sions' levels are quantified using a duty cycle. The duty cycle permits an
emissions' map for each pollutant to be condensed into a single number. An
emissions' map of N0 is shown in Figure 1.16

280 - \IZOO
24o— \\\\|000
200 ._ 800
300
:60 - 200 700
0' / 600
I —
“3:20 500
233
400
o . N 1

 

 

4CK) 800 HKXJIGOO 2000 2400
EINGINE SPEED RPM

Figure l. Nitric oxide (NO) emissions map in (gm/hr).
Reproduced from Boescher, R. E. and D. F. Webster, "Precombustion Chamber
Diesel Emissions--A Progress Report," Pres. Society of Automotive Engineers,
Vancover, BC, Aug. l6-l9, l97l, SAE Paper 7l0672, l3 pp.16

5

Diesel exhaust emissions data can be presented as either emissions flow rate
(grams per hour) or brake specific emissions rate (grams per brake horsepower
hour). The latter is simply the emissions flow rate divided by brake horse-
power to obtain the brake specific emissions rate. This report predominantly
uses brake specific emissions rate (grams per brake horsepower hour).

STUDY METHODOLOGY FOR THE ANALYSIS OF MSHA
DIESEL EXHAUST EMISSIONS DATA

This report analyzes exhaust emissions data for diesel engines. The emissions
data were collected by MSHA and analyzed by NIOSH. The eight engines are in-
direct injection (prechamber) engines: six naturally aspirated (NA) and two
turbocharged aftercooled (TA). The eight engines include two 4-cylinder, four
6-cylinder, one 8-cylinder, and one l2—cylinder engine.

Data for the eight diesel engines, along with the emissions data (in grams/-
brake horsepower hour) are shown in the Appendix. Each diesel engine is de-
signated by an identification number such as B-4 or D-8TAl. The first charac-
ter of the identification number is a code letter for the engine manufacturer.
The second character(s) is the number of engine cylinders. Additional letters
such as TA indicate turbocharged aftercooled and G indicates tests performed
in a methane atmosphere. GT indicates tests performed in l-percent methane
atmosphere.

All of the engines were tested in a methane-free atmosphere except the F-4,
which was tested in both a methane atmosphere and a methane-free atmosphere.
F-4 emissions data obtained in the methane atmosphere are indicated by F-4Gl.

The diesel engines were run on a dynamometer through a duty cycle consisting
of a Ininimum of nine static operating points, with up to eight additional
points in some cases. The nine basic operating points are rated speed with
25-, 50-, 75-, and lOO-percent power increments, peak Toad with the same power
increments, and idle. (Emissions data at idle were not available for this re-
port). The engines were brought to temperature equilibrium before exhaust
emissions were sampled.

Additional data collected include fuel rate and intake air rate (from vacuum
pressure measurements), which are used to calculate the fuel-to-air ratio.
Operating parameters recorded include engine speed, torque, horsepower, and
percent load. Atmospheric parameters recorded include dry bulb temperatures,
barometric pressure, dew point, and humidity (grains of H20/pound of dry
air). Atmospheric conditions of dry bulb temperature, humidity, and barometric
pressure while testing each engine are given in Table l.

The general procedures for testing diesel engines in nongassy (0-percent
methane) atmospheres are found under Schedule 24, Title 30, Part 32. For
gassy atmospheres (l- to l.5-percent methane), they are found under Schedule
31, Title 30, Part 36.11, 12

Diesel engines tested in this study were equipped with air cleaner, flame
arrestors, exhaust cooling, and exhaust systems. The emissions data are for
raw exhaust collected prior to any control devices. Diesel exhaust was

7

analyzed for N0, CO, and C02. Exhaust N02 emissions, which account for an
estimated 1- to 2-percent of the oxides of nitrogen, were not measured.17

Tabie 1. Test conditions of humidity, temperature and pressure.

 

 

Humidity Intake Air Barometric
Engine (grains HZO/ Temperature Pressure
Identification 1b dry air) (0F) (inches)

A-6 36-—40 45--67 28.82--28.87
8-6 38—-42 67-—80 29.08--29.18
E-6 32 60--66 29.32--29.39
E-6TA 48--70 67--86 29.17--29.60
B—4 2] 64--73 29.30--29.32
F-4 27--30 64-—77 29.25--29.29
F-4G] 26 79--82 29.22

D-8TA1 37--46 77--85 29.15—-29.38
A—12 64--74 59--71 29.16--29.98
Range for

all engines 21-—74 45--86 28.82--29.98

 

EVALUATION OF DIESEL EXHAUST EMISSIONS
AVERAGE DIESEL EXHAUST EMISSIONS FOR NO, C02, AND CO

The exhaust emission data for eight indirect injection (IDI) diesel engines
are shown in Table 2. The pollutants include N0, C02, and C0 in units of
grams per brake horsepower hour (gm/bhphr). The emission data were obtained
by averaging emissions for segments 3, 6, 9, and 10 of the Federal EPA l3-mode
cycle for heavy-duty diesel engines. Modes 3, 6, 9, and l0, plus l idle mode
of the l3-mode cycle, were recommended as the duty cycle for diesel equipment
used in underground mines by the Emissions Control Technology Work Group at
the NIOSH/Morgantown Diesel Workshop (September 1977). This duty cycle should
be used until specific information on underground diesel equipment duty cycles
is available.3 (Emissions data for the idle mode were not available and are
not included).

Table 2. Diesel engine exhaust emissions.*

 

N0 C02 c0
Engine Cylinder Type (gm/bhphr) (gm/bhphr) (gm/bhphr)

 

B-4 4 NA 4.2 600 1.6
F—4 4 NA 5.8 750 1.7
F-4Gl 4 NA 4.5 690 7.6
8-6 6 NA 4.2 640 1.9
A-6 6 NA 3.8 670 1.5
E-6 6 NA 5.6 812 2.4
E—6TA 6 TA 5.4 580 0.8
D-8TA1 8 TA 6.0 -- --
A-12 12 NA 4.6 700 2.3

 

*Based on Modes 3, 6, 9, and 10 of the Federal EPA heavy-duty diesel engine
l3-mode cycle.

Nitric oxide emissions ranged from 3.8 to 6.0 gm/bhphr. Lowest emissions were
from the 6-cylinder NA/IDI engine (A-6). Highest N0 emissions were produced
by the 8-cylinder TA/IDI engine (D-8TAl). The number of engine cylinders had
little effect on emission levels. N0 emissions for the 4-, 6-, 8-, and 12-

9

cylinder engines averaged 5.2, 4.8, 6.0, and 4.5 gm/bhphr, respectively. Com-
paring NA/IDI engines and the TA/IDI engines shows N0 emissions slightly higher
for the TA/IDI engines than for NA/IDI. NO emissions from NA engines averaged
4.8 gm/bhphr compared to 5.7 gm/bhphr from the TA engines.

All engines previously discussed were tested in a tnethane-free atmosphere.
However, the 4-cylinder NA/IDI engine (F-4) was also tested in a l-percent
methane atmosphere. The F-4 engine is designated as F-4Gl when tested in the
methane atmosphere. The data show reduced NO emissions in the methane atmo-
sphere (Table 2). F-4 engine emissions averaged 5.8 gm/bhphr in the methane-
free atmosphere compared to 4.5 gm/bhphr in the l-percent methane atmosphere.

C02 exhaust emissions, as shown in Table 2, ranged from 580 to 812 gm/bhphr.
€02 emissions averaged 704 gm/bhphr from the NA engines and 580 gm/bhphr from
the TA engines. Average 602 emissions from the TA engines were 21-percent
lower than from the NA engines. The methane atmosphere slightly reduced C02
emissions. In the l—percent methane atmosphere, the F-4 engine produced 690
gm/bhphr of C02 compared to 750 gm/bhphr in the zero-methane atmosphere.

C0 emissions, as shown in Table 2, ranged from 0.8 to 2.4 gm/bhphr for the
seven engines tested in the zero-methane atmosphere. CO emissions from the TA
engine (E-6TA) were much lower than C0 emissions from any of the NA diesel
engines. CO emissions from the E-6TA engine were half those of the A-6 engine,
which emitted the least CD of the NA engines. CO emissions from NA engines
averaged 2.0 gm/bhphr or about 2-l/2 times the CO emissions of 0.8 gm/bhphr
from the TA engine. The data also indicated the number of engine cylinders
had a small effect on CO emissions. The NA 4-, 6-, and l2—cylinder engine CO
emissions averaged 1.6, l.9, and 2.3 gm/bhphr, respectively, in the methane-
free atmosphere. In the case of the F-4 engine, CO emissions in the l-per-
cent methane atmosphere were four-and-one-half times C0 emissions in the
zero-methane atmosphere.

N0 EMISSIONS AT PEAK TORQUE AND RATED SPEED

Table 3 summarizes NO emissions (gm/bhphr) for peak torque; rated load and
speed; and the average of segments 3, 6, 9, and 10 of the EPA l3—mode cycle.
The data show that average N0 emissions (averaged over segments 3, 6, 9, and
TO of the l3-mode cycle) were higher than N0 emissions for either peak torque
or rated load and speed. These data point out that averaging N0 emissions
over four segments of the EPA cycle appears to be a more conservative approach
than using either peak torque or rated load and speed to regulate N0 emissions
from diesels.

The data also indicate there is little difference between peak torque N0 emi-
ssions and rated load/speed N0 emissions for NA engines. Data for one of the
two TA engines, E-6TA, show N0 emissions were significantly higher (35-per-
cent) at rated load/speed than at peak torque. However, N0 emissions at peak
torque and rated load/speed were the same for the other TA engines (D-8TAl).

Further examination of Table 3 shows that if diesel engines are ranked from
highest to lowest on the basis of N0 emissions (gm/bhphr), the engines will
be ranked almost the same whether the criteria is peak torque, the rated

10

load/speed, or the average over four segments of the EPA l3-mode cycle. For
example, the engine, D-8TAl, produced the highest N0 emissions at peak torque
when averaged over segments of the EPA cycle, and produced the second highest
N0 emissions at the rated load/speed.

Table 3. Diesel exhaust N0 emissions (gm/bhphr).

 

 

Average Modes Peak Rated Load
Engine 3, 6, 9, and l0 Torque and Speed
B-4 4.2 2.5 2.5
F-4 5.8 3.7 3.9
F-4Gl* 4.5 3.4 4.1
A-6 3.8 3.3 3.6
B-6 4.2 2.4 2.6
E-6 5.6 2.9 3.0
E-6TA 5.4 3.7 5.0
D-8TAl 6.0 4.6 4.8
A-lZ 4.6 3.3 3.8

 

*Operated in l-percent methane atmosphere

The data in Table 3 also show the TA engines produced higher N0 emissions than
the NA engines. This is true whether based on peak torque, rated load/speed,
or averaged over segments of the EPA cycle.

At rated load/speed, N0 emissions ranged from 4.8 to 5.0 gm/bhphr from the TA
engines and 2.l to 4.l gm/bhphr from the NA engines. Looking only at the
6-cylinder engines (A-6, B-6, E-6, and E-6TA) at rated load/speed, N0 emis-
sions from the TA engine (E-6TA) were higher than from the three NA engines.
Table 3 also shows the N0 emissions from the F-4 engine in the methane-free
atmosphere and the l-percent methane atmosphere. At peak torque and at rated
speed/load, N0 emission levels for the F-4 engine were about the same in the
methane-free and the l-percent methane atmosphere; however, averages over the
four segments of EPA cycle, N0 emissions were significantly lower in the
l-percent methane atmosphere than in the methane-free atmosphere.

Table 4 presents the N0 mass emissions rate (gm/hr) for eight diesel engines.
The turbocharged engines produced considerably more N0 (gm/hr) emissions than
the naturally aspirated engines. The 8-cylinder TA engine produced twice as
much N0 than the l2-cylinder NA engine, and the 6-cylinder TA engine produced
much higher N0 than any of the three 6-cylinder NA engines.

The NO mass emissions rate at rated speed/load is generally higher than the N0
mass emissions rate at peak torque or averaged over four segments of the EPA

ll

cyc1e. It is c1ear from the data that the N0 emissions rate depends 1arge1y
on the size of the engine or number of cy1inders, i.e., power output. Without
considering power output, it is very difficu1t to compare emissions' 1eve1s
for various engines. For this reason, diese1 engines are norma11y compared on
the basis of emissions per unit of power output and are reported in units of
gm/bhphr.

Tab1e 4. Diese1 exhaust N0 emissions (gm/hr).

 

 

Average Mode1s* Peak Rated Load
Engine 3, 6, 9, and 10 Torque and Speed
B-4NA 137 159 173
F—4NA 323 344 387
F-4G1NA 311 297 458
A-6NA 317** 394 486
B-6NA 199 185 270
E—6NA 419 388 422
E-6TA 762 822 1,320
D-8TA1 1,660 1,730 2,300
A-12NA 636 653 998

 

* From 13—mode EPA cyc1e.
**50-percent 1oad intermediate speed va1ue substituted for 25-percent
1oad intermediate va1ue which is missing.

EFFECT OF ENGINE SPEED, LOAD, FUEL/AIR RATIO, AND HORSEPONER 0N N0 AND CO
EMISSIONS

Speed and Load

Figure 2 shows N0 emissions from three diese1 engines: 4-cy1inder NA-IDI en—
gine (8-4), 6-cy1inder NA-IDI engine (B-6), and 6-cy1inder TA-IDI engine
(E-6TA). The emissions data were obtained at speeds and Ioads corresponding
to segments 3, 6, 9, and 10 of the EPA 13-mode cyc1e. At 25-percent 1oad and
intermediate speed (segment 3), there was 1itt1e difference in N0 emission
1eve1s among the three engines. In the other three modes, the data show the
N0 emissions from the two NA engines were significantIy 1ess than from the TA
engine.

Figure 2 a1so shows the re1ative importance of each of the four modes in deter-
mining an average N0 emission number, as found in Tab1es 2 and 3. For the NA
engines, N0 emissions at a 25-percent 1oad are much higher than for the three
segments with N0 emission 1eve1s progressive1y decreasing as 1oad increases
from 50- to 100-percent. In the case of the TA engine, N0 emissions are a1most

12

the same for 25-percent load-intermediate speed, 50-percent load-rated speed,
and 75-percent load-rated speed. At loo-percent load-intermediate speed, the
N0 emissions are significantly less than in the other three modes.

 

 

 

 

 

 

 

3-0 _ - 4 CYLINDER NA, no: (B4)
:1 6CYLINDER NA, IDI (86)
H ma 6 CYLINDER IDI (ESTA)
6.0 - I
N
N
{a i z
i; 4.C)r Ki ‘~
\ N N
E I t
3 N \
‘ E
0
\~ ‘~
N N
N N
N N
\
C)
SPEED INTERMEDIATE RATED RATED INTERMEDIATE
LOAD 25 50 75 IOO

(SEGMENT 3) (SEGMENT l0) (SEGMENT 9) (SEGMENT 6)

Figure 2. Nitric oxide emissions versus speed and
load (four segments of l3-mode cycle).

13

The effect of engine speed on NO emissions (gm/bhphr) is shown in Figures 3 and
4. Figure 3 shows N0 emissions from the NA-IDI engine (8-4). At 50-, 75-, and
lOO-percent loads, engine speed had little effect on NO levels. However, at
25-percent emission loads, N0 decreased slightly with increasing engine speed.

25% LOAD

/

 

T 5 '-

C

Q.

g 50% LOAD

S. a,“ c/0
V 4 —

C)

2 75 'I. LOAD

 

o\0’ Ar —o-o

 

 

 

3 _
I00 'lo LOA
(7” ’43" //):3 C)
2 I J I I l 4]
I700 I900 ZIOO 2300 2500 2700

ENGINE SPEED (mph)

Figure 3. N0 emissions versus speed and load (NA engine).

14

Figure 4 shows N0 emissions (gm/bhphr) from the TA-IDI engine (E-6TA). N0
emissions were affected by engine speed at all loads. At loads of 50-, 75-,
and lOO-percent, N0 emissions were about 50-percent higher at the rated speed
(2,200 rpm) than at the intermediate speed (1,600 rpm). At 25-percent load the
NO levels were only slightly greater at higher speed. The data in Figure 3
indicate that the B-4 NA engine can be operated between intermediate and rated
speed without affecting the N0 emissions. 0n the other hand, Figure 4 shows
that TA engine E-6TA should be operated closer to intermediate speeds to mini-
mize N0 emissions.

   
  
 
 

8 ~—
7 )— 257. LOAD
6 _
~ 50% LOAD
E
2
g /75-/. LOAD
E 5 —
O
\I00°/. LOAD
o
2
4 )—
3 .—
2 l l l I J

 

 

l600 l800 2000 2200 2400
ENGNE SPEED hpm)

Figure 4. N0 emissions versus speed and load (TA engine).

15

CO emissions for three diesel engines, 8-4, 3-6, and E-6TA, are shown in
Figure 5. C0 emissions are highest at 25-percent load intermediate speed and
decrease with increasing load. CO emissions from the TA engines are signifi-
cantly less than emissions from the two NA engines at 25-, 50-, and 75-percent
loads. At lOO-percent load, there is little difference in C0 emissions between
the NA engines and the TA diesel engines.

4.0T - 4 CYLINDER NA-IDI (34)
m 6 CYLINDER NA-IDI (BS)
E 6 CYLINDER TA-IDI (ESTA)

20-—

CO (gm/bhphr)

|.O—-

IIIIIIIIIIIlI/lllllll

 

 

 

 

 

25% 50 % 75% IOO %
INTERMEDIATE RATED RATED INTERMEDIATE

SPEED 8I LOAD

Figure 5. C0 emissions versus speed and load
(4 segments of l3-mode cycle).

16

CO emissions versus engine speed for a NA—IDI engine (8-4) is shown in Figure
6. CO emissions from the B-4 engine were not affected by engine speed except
at lOO-percent load. Here, C0 levels jumped slightly as engine speed increased
from 2,000 to 2,300 rpm. The data also show that CO emissions (gm/bhphr) are
halved as load is increased from 25- t0 50-percent and increasing the load from
50- to lOO-percent further reduces CO emissions. For mine application, the
data indicate it is better to select the smallest practical diesel engine and
operate it at higher loadings where CO emissions per unit of power are less.

25% LOAD

3.0-—

 

E

Q- 50 'lo LOAD

.C

.D

E v 0\0
o 7579 LOAD

U

z/o“'—-—~o

C C; /
|.O— // \o-o

 

 

 

/
o ————— o’
IOO v. LOAD
l l l J l
I600 l800 2000 2200 2400 2600

ENGINE SPEED (rpm)

Figure 6. CO emissions versus speed and load (NA engine).

17

FUEL/AIR RATIO

Figure 7 shows the dependence of exhaust N0 emissions on air/fuel (F/A) ratio
for three 101 diesel engines, a 4-cylinder NA-IDI (3-4) engine, a 6-cylinder
NA-IDI (E-6) engine, and a 6-cylinder TA-IDI engine (E-6TA). NO levels for all
three engines decrease with increasing F/A ratios. The data indicate that
additional air (oxygen) at lower F/A ratios ( .04) results in higher NO emis-
sions. The nearly identical slopes of the curves in the typical operating
ranges show the naturally aspirated and turbocharged aftercooled engines are
similarly affected by F/A ratio.

 

 

 

8.0 —
t 6.0 —
.c
O.
S
.D
\
e
3' 4.0 —
(D
2

2.0 —

l l l I I J
.0: .02 .03 .04 .05

FUEL-AIR RATIO

Figure 7 N0 emissions (gm/bhphr) versus F/A ratio.

18

N0 emissions are examined on a mass emission basis (i.e, gm/hr) in Figure 8.
The NA engines 8-4 and E-6 produced highest N0 mass emissions (gm/hr) at F/A
ratios between .030 and .045. The turbocharged aftercooled engine E-6TA pro-
duced very high NO emissions (gm/hr) at F/A ratios from .032 to .041 (there are
no data for F/A ratios greater than .041). In terms of mass emission rate, the
NA 6-cy1inder diesel (E-6) produced iower N0 emissions than the 6-cy1inder TA
engine (E-6TA). However, when the mass emission rates in Figure 8 are divided
by power output, the N0 emissions from these two engines are nearly identical
(as shown in Figure 7).

 

 

I200 -
\EGTA
IOOO —
t 800 —
.C
\
e
i?
S 600 —
as
/
400 —
a4
1 l l 1 1 J
.Ol .02 .03 .04 .05

FUEL-AIR RATIO

Figure 8. N0 emissions (gm/hr) versus F/A ratio.

 

The 8-cy1inder TA-IDI engine (D—8TA1) N0 mass emissions rate (gm/hr) for a
range of F/A ratios is shown in Figure 9. N0 mass emissions increase signifi-
cant1y as the F/A ratio increases from 0.024 to 0.037. Figure 9 a1so shows
that higher engine speed increases the N0 mass emissions from the D-8TA1 en-
gine. For examp1e, at the F/A ratio of .034, the N0 mass emissions rate was
1,450 gm/hr at 1,800 rpm and 1,900 gm/hr at 2,100 rpm, an increase of approxi-
mate1y 30—percent.

 

 

25CX)r-
ZIOO rpm
2CXDC)-
E o
-
E; ISCXD '-
IBCXDrpni
(D
Z
l()CND '-
l l l J I
.020 .025 .030 .035 .040

FUEL-AIR RATIO

Figure 9. NO emissions versus F/A ratio and engine speed.

20

The effect of F/A ratio on the C0 emissions (gm/bhphr) from three diesel en-
gines, 8-4, E-6, and E-6TA, is shown in Figure 10. CO emissions from all three
‘engines were lowest at F/A ratios between 0.032 and 0.045. The data also show
one TA engine (E-6TA) produced significantly lower C0 emissions than the two NA
engines. C0 emissions from the E-6TA were half the CO emissions for NA engines

in the F/A range of 0.032 to 0.045.

 

 

 

5.0 —
4.0 '—
E
2 3.0 —
1:
-
E
3
(3 2.C>-
U
l.0 —
I I l I I
Ol 02 .03 04 05

FUEL-AIR RATIO

Figure 10. CO emissions (gm/bhphr) versus F/A ratio.

21

Figure 11 shows CO mass emissions rate (gm/hr) for the above three engines.
The minimum C0 mass emissions occurred at F/A ratios from 0.028 to 0.037. C0
mass emissions for the E-6 and E-6TA engines increased with F/A ratios below
0.028 or above 0.037. The 8-4 engine C0 mass emissions increased at F/A ratios
above 0.037 but did not increase at F/A ratios less than 0.028. It is not
clear why decreasing the F/A ratio beiow 0.028 affected C0 emissions from the
E-6 and E-6TA engines, but not the B-4 engine.

 

 

200—
as
\
3 I50—
\
5
0| A.
v \\
A
8 IOO— esm/ \ //
\A,A
\34
50_
l I l l I I
.0: .02 .03 .04 .05

FUEL-AIR RATIO

Figure 11. C0 emissions (gm/hr) versus F/A ratio.

22

CORRELATION OF HORSEPOWER, F/A RATIO, AND FUEL RATE

The horsepower and F/A ratio show a direct correlation as illustrated in
Figures l2 and l3. Figure l2 presents the relationship between horsepower and
F/A ratio for a 4-cylinder NA-IDI engine (3-4) and a 6-cylinder NA-IDI engine
(A-6). The data in Figure 12 were obtained at engine speeds ranging from
1,700 to 2,594 rpm for engine B-4, and from l,900 to 2,409 rpm for engine A-6.
The relationship of horsepower to F/A ratio is essentially linear. There is
some scatter at high F/A ratios above 0.04 in which engine speed has a more
pronounced effect on the relationship of horsepower and F/A ratio.

:407

l20-—

l0C)-

6C)-—

HORSEPOWER

4o—

 

! J l l l I I
.05 .020 .025 .030 .035 .040

FUEL-AIR RATIO

 

Figure l2. Horsepower versus F/A ratio.

23

In Figure 13, horsepower is plotted against the F/A ratio for an 8-cyiinder
TA-IDI engine (D-8TA1). The data are presented for two engine speeds, 1,800
rpm and 2,100 rpm. The data show that, at the same F/A ratios, higher engine
speed results in higher horsepower. For example, at the F/A ratio of 0.030,
the horsepower is 35—percent higher at an engine speed of 2,100 rpm than at

1,800 rpm.

 

 

 

500 —
400 —
a:
m
5
a 300 —
U
U)
m
(D
I
200 —
IOO —
l I l L I
.020 .025 .030 .035 .040

FUEL-AIR RATIO

Figure 13. Horsepower versus F/A ratio and engine speed.

24

Figure 14 relates horsepower to fuel rate (pounds/hour) for three diesel en-
gines. For the 6—cylinder NA-IDI engine (E-6), the relationship of fuel rate
to horsepower is linear up to 75-percent load (l02 hp). Above this load, the
fuel rate per unit of horsepower increased. The relationship of fuel rate to
horsepower is also linear up to 50-percent load for the 6-cylinder NA-IDI en-
gine (A-6). Above this, the fuel rate per unit of horsepower increases. The
E-6TA engine has a slightly higher fuel rate per unit of horsepower at loads
50-percent and above than at loads of 25-percent.

300'—

250'—' /;{

zoo — o/

S‘CYLINDER TA-IDI\ /
(ESTA) /

I50 — /

HORSEPOWER

   

 

 

o
6-CYLINDER NA-IDI ,
(A6) y»
IOO -— '
'CYLINDER NA-IDI
(E6)
so r-
l I l l L I
20 4o 60 80 IOO

FUEL RATE (lbs/hr)

Figure l4. Horsepower versus fuel rate (at 2,000 rpm).

25

Figure l4 also indicates the relative energy efficiency of these three diesel
engines. The E—6 engine uses slightly more fuel per unit of power than the
other two engines. It appears that fuel efficiency for the three engines is
not affected by the type of air intake system, i.e., by whether it is a NA or
TA engine.

EFFECT OF HORSEPOWER ON EMISSION LEVELS

N0 emissions (gm/bhphr) from three diesel engines operating at 2,000 rpm are
shown in Figure 15. The three engines are a 4-cylinder NA-IDI engine (8-4), a
6-cylinder NA-IDI engine (8—6), and a 6-cylinder TA-IDI engine (E-6TA). The
effect of horsepower on the two naturally aspirated engines is clear. Increa-
sing horsepower results in a significant decrease in N0 emissions per unit of
power. This would indicate it is preferable to use the smallest engine for
each particular application so the engine would operate in a higher power
range where N0 emissions would be lower. The data in Figure l5 also show the
4-cylinder engine produces lower emissions than the 6-cylinder for the same
horsepower. For example, at 40 horsepower, N0 emissions were 3.6 and 4.7
gm/bhphr for the 4—cylinder and 6-cylinder NA engines, respectively. The
6-cylinder TA engine (E-6TA) produced significantly higher N0 emissions at the
same horsepower than either of the two NA engines. The data also show that the
E-6TA engine N0 emissions (gm/bhphr) were constant at loads above 50-percent,
unlike the NA engines where N0 emissions decreased as loads increased from 50-
to loo-percent. If N0 emissions become the principal criterion in determining
the suitability of diesel engines in mines, NA engines appear to have an ad-
vantage over TA engines.

G'CYLINDER TA

 

 

 

,. l’X / (ESTA)
E
a 6.0 \ -
s F
\ \ \
E» \. fir ~0—
0 4 O L— 0\ A\/6'CYL|NDER NA
2 . \ . \ (as)

4-CYLINDERO A.

NA (B4)’\o\ \'u
2.0 l I I‘ I l l I I
O 40 80 |20 I60 200 240 280
HORSEPOWER

Figure l5. N0 emissions versus horsepower (at 2,000 rpm).

26

C0 emissions from the three diesel engines 8-4, 8—6, and E-6TA are shown in
Figure 16. CO emissions (gm/bhphr) are much higher at low load (and horse-
power) than at high load (and horsepower), particularly in the case of the two
NA engines. C0 emissions from the two NA engines, 84 and B6, are halved as the
power is doubled 25- to 50-percent load. Comparing the two engines shows the
4-cylinder engine (8-4) produced lower C0 emissions than the 6-cylinder engine
(8-6). As noted previously, the 8-4 engine also produced lower N0 emissions
than the 8-6 engine. Exhaust CO emissions (gm/bhphr) from the TA diesel engine
E-6TA greatly decreases (70-percent) as the power increased from 66 to 130
horsepower and the load from 25- to 50-percent. CO emissions (gm/bhphr) were
constant as loadings increased from 50- to lOO-percent.

 
  
   

 

 

4.0 -
i
Q
3.0-— \/6'CYLINDER NA (36)
E
D.
S
\
g 2.0—
V \
o D\ 6—CYLINDER TA (ESTA)
° \
IO" \Au—‘A /
n \‘
4-CYUNDER// \\‘-n-
NA (34) ~--—_D_-.-.___fl.
l L l l l l I
o 40 80 I20 ISO 200 240 280

Figure 16. C0 emissions versus horsepower (at 2,000 rpm).

27

EMISSIONS IN A METHANE ATMOSPHERE

N0 emissions data for a 4-cylinder NA-IDI diesel engine (F—4) in the methane
and methane—free atmospheres are shown in Figure 17. The data were collected
at an engine speed of 2,000 rpm. The l-percent methane atmosphere signifi-
cantly affected the NO emissions (gm/bhphr) at low-to-medium power (25 to 50
horsepower). For example, at 27 horsepower (25-percent load), N0 emissions in
the l-percent methane atmosphere were half NO emissions in the methane-free
atmosphere. As horsepower increased, the methane atmosphere had less effect
on NO levels. At lOO-percent load, N0 emissions in the methane and methane-
free atmospheres were identical. The methane atmosphere could possibly affect
ventilation requirements for underground mines using diesels. For instance,
if a diesel were operated largely in a low/medium power range, and NO were the
critical emission, the methane atmosphere would lessen N0 emissions and might
possibly lessen the amount of ventilation required.

    

 

 

8.0 ’—
O-PERCENT CH4
/////;IMOSPHERE
6.0 -
/
’C , /
g '\
a /
\
g, I-PERCENT CH4
5 ATMOSPHERE
2 2.0 —
| I I I I J
O 20 4O 60 80 I00 I20
HORSEPOWER

Figure l7. N0 emissions versus horsepower with and without
CH4 atmosphere (at 2,000 rpm).

28

The effect of the methane atmosphere on carbon monoxide (CO) emissions from a
4-cylinder NA-IDI (F-4) diesel engine is presented in Figure l8. It shows the
dramatic increase in C0 emissions resulting from the l—percent concentration
of methane. With full power, the CO concentration in the methane atmosphere
was two-and-one-half times the CO concentration in the methane-free environ—
ment. At low/medium power, CO emissions were even higher in the methane at-
mosphere. For example, at 25—percent load (27 hp), C0 emissions were about
six-times higher in the l-percent methane atmosphere than in the methane-free
atmosphere; and at 50-percent load (54 hp), C0 emissions were five-times higher
in l—percent methane than in the methane-free atmosphere.

A

\

l6.0 )- \
ATMOSPHERE

\
\/

I2.0 '—
\

 

 

 

fl
.2
e 80 \A
S ' \\
8 NO-METHANE \\
ATMOSPHERE
4.0 -
J l
O 20 4O 60 80 IOO |20

HORSEPOWER

Figure l8. C0 emissions versus horsepower with and without
CH4 atmosphere (at 2,000 rpm).

29

The diesel emissions data were collected in humidities ranging from 21 to 74
grains of H20 per pound of dry air (gr H20/lb dry air). Studies have shown
that NO exhaust emissions are affected by the humidity and several correction
factors have been developed to correct of humidity. In one study sponsored by
the Coordinating Research Council (CRC), a correction factor, K, was developed
to adjust N0 emissions data for humidity.18 This factor is calculated using
the following equation:

l
K = —i - 0.00" 3‘3‘7—6 H-7‘5")

where H = the humidity of the inlet air in gr (H20)/lb dry air.

At 75 gr (H20)/lb dry air, K is equal to l. Below 75 gr (H20)/lb dry air,
it is less than l; and above 75 gr (H20)/lb dry air, it is more than 1.
Therefore, when the humidity is less than 75 gr (H20)/lb dry air, corrected
N0 emission levels are less than uncorrected NO levels; and above 75 gr
(H20)/lb dry air, vice versa.

N0 emissions data corrected and uncorrected for humidity are shown in Figure l9
and Table 5. The 4-cylinder NA-IDI engine F-4 was tested in an atmospheric
humidity of 28 to 30 gr (H20)/lb dry air. The "K" value for 28 gr/lb dry air
is 0.86. This factor multiplied by 25-percent load N0 emissions value of 6.9
gm/bhphr gives a humidity corrected N0 emissions value of 5.9 gm/bhphr, as
shown in Table 5. The 6-cylinder NA-IDI engine 8-6 was tested in an atmos-
pheric humidity from 38 to 40 gr (H20)/lb of dry air. The "K" value is 0.89
for a humidity of 38 gr (H20)/lb dry air. Data for the 8-6 engine are also
shown in Table 5.
Table 5. N0 Emissions Uncorrected and
Corrected for Humidity.

 

Humidity N0 “Uncor- N0 "Cor-
gr (H20)/ rected" rected"
Engine Speed (rpm) % Load lb dry air "K"* (gm/bhphr) (gm/bhphr)

 

F-4 2,000 25 28 .86 6.9 5.9
F-4 2,000 50 30 .87 6.9 6.0
F-4 2,000 80 30 .87 5.4 4.7
F-4 2,000 100 30 .87 3.9 3.4
8-6 2,000 25 38 .89 6.3 5.6
B-6 2,000 50 38 .89 4.3 3.8
8-6 2,000 75 38 .89 3.3 2.9
8—6 2,000 100 40 .89 2.4 2.1

 

*Ref 18: CRC No. 447. “Effect of Humidity..."

30

N0 (gm lbhphr)

8.0

9‘
o

:5
o

2.0

 

    

4'CYLINDER NA - I DI

   

(F4)

 

PERCENT LOAD

r
CORRECTED FOR
\ HUMIDITY
/\
G'CYLINDER NA
IDI (as) ‘\
\

- \‘y

l I l l l

25 50 75 IOO

Figure 19. N0 emissions versus load and humidity.

31

CONCLUSIONS

Nitric oxide (NO) emissions are higher from turbocharged aftercooled (TA)
diesel engines than from naturally aspirated (NA) engines (based on com-
parison of indirect injection engines). Carbon monoxide (CO) emissions
were considerably less from TA engines except at l00-percent load, where
CO emissions for both NA and TA engines were the same.

The data show that the number of engine cylinders had almost no effect on
indirect injection diesel exhaust NO or C0 brake specific emissions (i.e.,
gm/bhphr).

Brake specific N0 emissions (gm/bhphr) averaged over segments 3, 6, 9, and
10 of the EPA lB-mode cycle, were higher than NO levels at peak torque or
at rated load/speed.

Brake specific N0 emissions (gm/bhphr) decreased with increasing
fuel-to-air (F/A) ratio up to a F/A of 0.050. (Data for F/A ratios above
0.050 were not available.) C0 emissions were lowest in the range of F/A
ratios from 0.032 to 0.045.

Both N0 and CO (gm/bhphr) emissions decreased considerably as horsepower
increased, as would be expected in brake specific terms.

A diesel engine, indirect injection--naturally aspirated, produced signi—
ficantly less N0 emissions in the l-percent methane atmosphere than in the
methane-free atmosphere when operated in low-to-medium power range. How-
ever, at high power (lOO-percent load), diesel N0 emissions were about the
same in the l-percent methane and the methane-free atmospheres. (At 100-
percent load, the engine produced greater horsepower with the methane
atmosphere than without it.) CO exhaust emissions increased greatly in
the methane atmosphere.

32

 

RECOMMENDATIONS

Research should be concentrated on the collection and evaluation of emis-
sions data for diesel engines with the control devices attached. The
following types of diesel engines with selected exhaust control devices
should be tested: (l) direct injection naturally aspirated; (2) direct in-
jection turbocharged—aftercooled; (3) indirect injection naturally aspi-
rated; and (4) indirect injection turbocharged-aftercooled. Although
indirect injection engine raw exhaust emissions are generally lower,
direct injection engines in combination with certain control devices may
produce lower emissions than indirect injection engines with the same con-
trol device.

The data in this report show that emissions vary even among diesel engines
of the same number of cylinders, fuel injection system, and air intake
system (e.g., 6-cylinder IDI-NA engines). Therefore, the effective con-
trol devices should be tested on several makes of the same engine type.

Future studies should include diesel exhaust emissions data with/without
control devices at loads from idle to 20-percent. One reviewer noted that
N02 can be a significant portion of NOx at idle and low speeds. (Any
future studies of emissions at idle speed should note that emissions in
gm/bhphr at idle would be infinite, since horsepower at idle is zero.)

The duty cycle of underground mine diesels must be assessed to determine
the importance of transient conditions on emissions. A study to assess
duty cycles sponsored jointly by NIOSH and the U.S. Bureau of Mines is
presently underway.

This report was confined to gaseous emissions; however, future work should
concentrate on oxygenates, particulates, and organics adhering to or ab-
sorbed on particulates.

Information on exhaust emissions for diesels operated at high elevations
(3,000 to l0,000 feet) should be obtained. At higher elevations, the sto-
chiometry is different and a greater potential to pollute exists with re-
duced combustion air.

MSHA, when certifying engines for use in underground mines, should con-
sider measuring diesel exhaust emissions following installation of control
devices and, thus, include any benefits of the controls in reducing over—
all ventilation requirements.

33

l0.

ll.

l2.

REFERENCES

Statement of Edward J. Baier, Deputy Director, NIOSH, before the Sub-
committee on Energy Research, Development and Demonstration House Com-
mittee on Science and Technology, July 27, 1976, p. 8.

Health Effects of Diesel Exhaust Emissions Prepared for the American
Mining Congress, Environmental Health Associates, Inc., Berkeley, CA,
January 25, l978, pp. 80-l.

The Use of Diesel Equipment in Underground Coal Mining, NIOSH, Morgan-
town, WVA, September 19-23, l977, p. 110.

Johnson, J. H., Diesel Engine Design, Performance, and Emission Charac-
teristics, Proceedings of Symposium on Use of Diesel Powered Equipment in
Underground Mining, Pittsburgh, PA, January 30-3l, l973.

Hurn, R. N., Diesel Emissions Measurement and Control, Proceedings of
Symposium on the Use of Diesel Powered Equipment in Underground Mining,
Pittsburgh, PA, January 30-3l, l973.

Henderson, R. 0., Diesel Technology, Proceedings of Symposium on the Use
of Diesel Powered Equipment in Underground Mining, Pittsburgh, PA,
January 30-31, l973.

Bristow, N., Trackless Transport for Men and Materials, Mining Technology
Clearing House, Nos. l-3, Staffordshire, England B797Af, May, 1978.

Determination of Breathing Zone Concentrations of Contaminants from Emis-
sions from Diesel Powered Vehicles in Underground Mines, U.S. Bureau of
Mines (Part II, Contract No. J0 25500l), l974-76.

Alcock, K., Duty Cycles and Load Factors of Diesel Powered Vehicles in
Underground Mines, American Mining Congress, l978.

Dainty, E. D. and G. K. Brown, Federal Certification and Research Con-
cerning Environmental Aspects of Diesel Powered Machines in Coal Mines,
CIM Bulletin, pp. 80-95, November 1974.

Title 30, Part 32 (Schedule 24), Federal Register, Vol. T4, N0. 67, pp.
l84-195, April 8, l949.

Title 30, Part 36 (Schedule 3l), Federal Register, Vol. 26, No. 14,
January 24, l961.

34

13.

14

15.

16.

17.
18.

Higginson, N., Use of Diese1 Engines Underground in British Coa1 Mines,
Proceedings of Symposium on the Use of Diese1 Powered Equipment in Under-
ground Mining, Pittsburgh, PA, January 30-31, 1973.

A1cock, K., Written Comments Submitted After the Symposium, Proceedings
of Symposium on the Use of Diese1 Powered Equipment in Underground
Mining, Pittsburgh, PA, January 30-31, 1973.

Marsha11, w. F., Emission Contro1 for Diese1s Operated Underground:
Cata1ytic Converters, ERDA-BERC, August 1975.

Boescher, R. E. and D. F. Webster, Precombustion Chamber Diese1
Emissions--A Progress Report, Pres. Soc. of Automotive Engineers,
Vancouver, B.C., SAE Paper 710673, 13 pp., August 16-19, 1971.
Sharp, F., Persona1 Communications, MSHA, Bruceton, PA, 1978.
Effect of Humidity of Air on Nitric Oxide Formation in Diese1 Exhaust,

Coordinating Research Counci1, Inc., No. 447, p. 18, New York, December
1971.

35

 

APPENDIX
DIESEL ENGINE TEST DATA

37

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ENGINE B4 AVERAGE

TEST NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

RPM 1700 2500 2500 2544 2570 2594 2500 2500 2500 2300 2300 2300 2300 2000 2000 2000 2000 1700 1700 1700

PERCENT LOAD 25 100 100 75 50 25 75 50 25 100 75 50 25 100 75 50 25 100 75 50
FUEL/AIR .014 .044 .045 .034 .026 .018 .034 .025 .017 .043 .032 .023 .016 .041 .031 .022 .014 .040 .030 .021

N0 (gm/bhphr) 6.8 2.5 2.4 3.4 4.4 5.8 3.4 4.2 5.8 2.5 3.3 4.2 6.0 2.5 3.2 4.3 6.4 2.5 3.4 4 5 4.1
(:02 (Gm/bhphr) 714 572 573 567 606 782 557 600 770 583 548 569 746 541 541 563 741 547 542 562 610
(:0 (gm/bhphr) 3.2 1.2 1.1 1.0 1.5 3.1 1.0 1.6 3.2 1.2 1.1 1.6 3.3 .8 1.1 1.6 3.4 .8 1.1 1.7 1.7
TORQUE (loo-percent 151 151 156 159 159

load)
HORSEPOWER 12.8 71.8 71.8 54.6 37.3 18.8 53.7 36.2 18.1 68.5 51.3 34.6 17.3 60.7 45.6 30.6 15.0 51.6 38.8 26.0
W
\O
ENGINE F4 AVERAGE

TEST NUMBER 1 2 3 4 S 6 7 8 9 10 ll 12

RPM 2306 2200 2200_ 2200 2000 2000 2000 2000 1800 1800 1800 1800

PERCENT LOAD 25 80 50 25 100 80 50 25 100 80 50 25

FUEL/AIR .020 .039 .028 019 .049 .038 .025 .018 .049 .038 .026 .017

N0 (gm/bhphr) 6.6 5.4 6.7 7.0 3.9 5.4 6.9 6.9 3.7 5.2 7.3 7.3 6.0

CO; (Gm/thhr) 1107 690 779 1093 654 656 735 999 622 627 676 928 800

C0 (gm/bhphr) 6.5 1.0 1.7 5.1 .8 1.0 1.6 3.3 .8 1.0 1.6 3.2 2.3
TORQUE (loo—percent 259 272

load)

HORSEPOWER 27 81 51 25 99 79 49 25 93 74 46 23

 

0‘7

ENGINE E6

AVE RAGE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TEST NUMBER 1 2 3 4 5 6 7 8 9 10 11 12
RPM 2200 2200 2200_ 2200 2000 2000 2000 2000 2200 2287 2313 2332
PERCENT LOAD 100 75 50 25 100 75 50 25 100 100 100 100
FUEL/AIR 4052 .037 .028 .020 .050 .036 .026 .017 .052 .039 .030 .021
No (gm/bhphr) 3.0 5.3 6.8 7.3 2.9 5.2 7.1 7.5 3.0 5.4 6.6 7.3 5.6
co; (Gm/bhphr) 722 714 794 1147 693 666 730 1018 720 752 815 1152 830
co (gmehphr) 1.6 1.1 1.7 5.2 1.2 1.1 1.7 5.1 1.6 1.1 1.7 5.1 2,4
TORQUE (IOU-percent 338 352 338 254 169 85
load)
HORSEPOWER

ENGINE B6 AVERAGE
TEST NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
RPM 2500 2550 2575 2584 2500 2500 2500 2300 2300 2300 2300 2000 2000 2000 2000 1700 1700 1700 1700
PERCENT LOAD 100 75 50 25 75 50 25 100 75 50 25 100 75 50 25 100 75 50 25
FUEL/AIR .046 .034 .025 .018 .034 024 .017 .045 .033 .023 .016 .044 .032 .022 .015 .043 .032 .023 015
N0 (gm/bhphr) 2.6 3.3 4.4 5.9 3.4 4.3 5.3 2.5 3.2 4.3 5.8 2.4 3.3 4.3 6.3 2.4 3.2 4.7 6.6 4.1
(:02 (Gm/bhphr) 616 608 658 913 618 646 849 597 574 616 805 568 565 590 769 560 543 572 750 650
co (gm/mph“ 1.6 1.6 1.6 3.2 1.6 1.6 3.3 1.2 1.6 1.6 3.2 1.1 1.0 1.6 3.3 1.1 1.0 1.5 3.2 1.9
TORQUE (loo-percent 217 234 237 238
load)
HORSEPOWER 103.4 79.4 53.2 27.1 77.9 51.7 26.2 102.0 77.2 51.3 25.9 90.2 67.7 45.1 22.6 77.1 58.0 38.8 19.2

 

 

1‘7

ENGINE D8TAl

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AVG.
TEST NUMBER 1 2 3 4 5 6 7 a 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
pm 2100 2100 2100 2100 2100 2100 2100 2100 2100 2100 2000 2000 2000 2000 2000 1900 1900 1800 1800 1800 1800 1800 1600
psaczm LOAD 100 95 89 84 79 68 63 53 42 32 100 65 54 43 33 100 91 100 63 60 48 3: 100
magma .037 .036 035 .034 .034 .033 .031 .029 027 .024 .038 .033 .031 .028 .025 .038 .036 .037 .034 .032 .030 .027 038
1:0 (gn/bhphr) 4.8 4.9 5.0 5.0 5.1 5.3 5.5 6.0 6.7 7.9 4.7 5.4 5.9 6.7 8.1 4.6 4 8 4.9 5.5 5.5 6.6 7.9 4.6 5.7
co; (Gm/bhphr) 572 592 617 660 713 583 605 641 695 581 588 616 648 620
00 (gm/bhphr) .5 .6 .6 .7 .8 .5 .6 1.3 1.6 1.0 .5 .6 1.4 0.8
7?:332 (loo-percent 1187 1208 1216 1225 230
HORSEPOWER 475 450 425 400 375 325 300 250 200 150 460 300 250 200 150 440 400 420 265 250 200 150 375
ENGINE E6TA AVG_
TEST NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
mm 2200 2200 2200 2200 2000 2000 2000 2000 1900 1900 1900 1900 1800 1800 1800 1800 1600 1600 1600 1600 2250 2282 2301
psaczm 170710 100 75 50 25 100 75 50 25 100 75 50 25 100 75 50 25 100 75 50 25 75 50 25
yumfla .041 .037 .032 .022 .043 .039 .034 .023 .044 .038 .031 .024 .044 .041 .035 I023 .047 .043 .036 .023 .035 .032 .023
1:9 (gm/bhphr) 5.0 5.4 6.0 7.1 4.7 4.9 5.2 7.0 4.5 4.7 5.4 6.8 4.3 4.4 4.9 6.4 3.7 3 7 4.2 6.5 5.5 6.2 6.8 5.4
cg; (Gm/bhpnr) 563 564 587 728 556 540 514 666 543 543 548 651 541 543 543 638 550 562 553 618 578 613 757 590
00 (Mhphr) .4 .5 .6 1.9 .4 .4 .5 1.7 .8 .4 .5 1.7 .4 .4 .5 1.7 .7 4 .5 1.6 .5 .6 2.0 0.8
TORQUE (loo-percent 628 684 698 711 730
load)
HORSEPOWER 263 197 132 66 260 195 130 66 252 189 126 63 244 183 122 61 222 167 111 56 187 135 69

 

 

Z‘7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ENGINE A6 AVG_
TEST NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
may. 2409 2390 2365 2300 2300 2300 2300 2200 2200 2200 2200 2100 2100 2100 2100 2000 2000 2000 2000 1900 1900 1900 1900
FERCENT 1.0110 100 100 100 100 85 7o 50 100 85 70 50 100 85 7o 50 100 85 70 50 100 85 70 50
FUEL/AIR .025 .031 .036 .041 .036 .030 .024 .042 .036 .030 .024 .042 .037 .030 .024 .042 .036 .030 .023 .042 .037 .030 .023
1:3 (qw/bhphr) 4.5 4.0 3.9 3.6 3.8 3.9 4.3 3.4 3.6 3.7 3.8 3.4 3.4 3.6 3.5 3 3 3.5 3 5 3 5 3.3 3.5 3.5 3.6 3.7
C02 (Gm/mp“) 767 674 648 665 642 659 762 638 624 637 709 634 625 651 674 628 611 607 668 606 595 597 658 650
co (gm/bhphr) 1.8 1.3 1.1 .9 1.1 1.3 1.9 .9 1.0 1.3 1.8 1.3 1.0 1.3 1.7 1.3 1.0 1.2 1.7 1 2 1.0 1.2 1.7 1.3
TORQUE (loo-percent 154 216 262 307 313 319 327 330
load)
HORSEPOWER 71 98 118 135 115 94 67 131 111 92 65 127 108 89 64 125 106 87 62 119 101 84 59
ENGINE A12 AVG.
TEST NUMBER 1 2 3 4 5 L 7 3 9 10 1] 1; 12 1A 15 16 17 18 19 20 21 22 23
PPM 2452 2433 2415 2300 2300 2300 2300 2100 2100 2100 2100 1900 1900 1900 1900 1700 1700 1700 1700 1500 1500 1500 1500
125303;? 170210 100 100 100 100 75 50 25 100 75 50 25 100 75 50 25 100 75 50 25 100 75 50 25
FUEL/AIR .019 .026 .034 .044 .033 .024 .017 .044 .032 .025 .017 .042 031 .023 .016 .042 031 .023 .015 .043 .032 .023 .015
N0 (gmehphr) 7.2 5.9 5.0 3.8 4.8 5.3 6.9 3.7 4.4 4.8 5.8 3.7 4.5 4.3 5.5 3.6 4.0 3.9 4.8 3 3 4.3 4.1 5.0 4.7
C02 (Gm/bhphr) 1110 775 709 678 688 748 1106 629 636 712 997 605 631 698 940 587 584 633 868 568 565 584 800 730
co (gm/bhphr) 3.6 1.8 1.2 1.3 1.2 1.8 3.7 .8 1.2 1.8 5.4 .9 1.2 1.8 5.6 .8 1.1 1 7 5.3 1 2 1.1 1.6 5.1 2.2
TORQUE (loo-percent 151 300 450 599 620 619 649 684

load)

HORSEPOWER

 

 

{*7

n4

.y

VVOl/LV['199"086[3331350 DNILNIHd lKBNNHBAOS

ENGINE F4Gl

AVERAGE

 

 

 

 

 

 

 

 

 

TEST NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

RPM 2200 2239 2278 2299 2200 2200 2200 2000 2000 2000 2000 1800 1800 1800 1800

PERCENT LOAD 100 80 50 25 80 50 25 100 80 50 25 100 80 50 25

FUEL/AIR .053 .044 .031 021 .042 .030 .020 .057 .042 .028 .019 .055 .041 .027 .018

NO (qrn/bhphr) 4.1 5.9 5.5 4.2 5.8 4.8 4.0 3.6 5.6 5.2 3.8 3.4 5.6 5.5 3.9 4,7
C02 (Gm/bhphr) 661 669 731 972 633 693 957 646 636 661 858 626 606 622 826 720
co (gm/thhr) 1.8 2.2 8.6 20.1 2.7 8.8 20.8 2.1 2.6 8.5 18.7 2.0 2.6 8.3 17.0 8,5
TORQUE (loo-percent 269 285 298

load)

HORSEPOWER 113 92 59 30 90 57 28 108 87 54 27 102 82 51 26

 

GENERAL UBBAHY-ILC.BEHKELEY

BDDUHQIELL