14

contribute less than 8 pet to the total SDPM for non-
catalyzed engines. The fact that SDPM remained un-
changed (fig. 12) at 244 h suggests that some unknown
factor may have been involved to ensure that nonvolatile
sulfate increases were balanced by nearly equal carbon and
SOF reductions.

For catalyzed systems the sulfate levels are expected to
be greater (30). The development of a catalytic oxide
coating and changing sulfate levels can account for the
DPM variability with conditioning time that was observed
for the RDC. The reduced GPHC at 46 h (fig. 5) could
account for the DPM reduction also observed at that point
in the conditioning process. As conditioning proceeded,
the catalytic reactions of the developing ferric oxide
deposits caused increased sulfate levels, accounting for the
increased DPM at 101 h. Finally, at 244 h, the ferric oxide
coating was sufficiently developed to significantly reduce
both carbon and GPHC. The order of catalytic oxidation
effects suggested here is consistent with the temperatures
at which GPHC, SO,, and carbon oxidize—hydrocarbons
oxidize at the lowest temperature and carbon at the
highest.

As noted earlier, the results shown for VDPM and
SDPM (figs. 18-19) suggest that all the DPM reductions
observed were the result of VDPM (SOF) reductions, a
conclusion that may be true for engine modes at low
fuel-air ratios where SOF levels are high—up to 50 pet
(32). On the other hand, the large DPM reductions, of
about 20 and 30 pet for modes 6 and 14 cannot be the
result of VDPM reductions, because the VDPM levels for
these two modes are less than 5 pet for the unconditioned
engine (32). Furthermore, estimates in figure 18 suggest
that sulfates may contribute significantly to VDPM at
modes having high fuel-air ratios. Therefore, the inference
is that the observed DPM reductions must be the result of
reduced carbon levels.

In figure 20 two sets of data are combined: the sulfate
contributions to DPM from figure 17 and the DPM
reductions at 244 h from figure 10. The striking feature is
that the two curves are almost mirror images. The com-
parison strongly suggests that the observed DPM changes
were greatly influenced by sulfates and tends to confirm

the inferences in the preceding discussions. Note espe-
cially that the sulfate levels (fig. 20) are for the uncon-
ditioned engine. Conversion rates increase with the use of
oxidation catalytic converters (30). In other words, the
sulfate interference for the conditioned engine is probably
underestimated in figure 20.

8 T
3 7PT 7
a
3 of |
3
& st J
&
G Engine speed
3
B sb © Ide 4
z © 1,600 r/min
8 ab od 4 2,300 r/min 4
1 1 1 . 1.
° 01 0.04 0108
Figure 19.—Effect of fu timated sulfate fraction

In solid DPM (SDPM). Data labels are test modes.

2
8

; EN
L KEY

© Estimated sulfate levels in DPM
v Measured DPM reductions

DPM REDUCTION OR SULFATES, pct
3

° 0.02 0.04
FUEL-AIR RATIO

0.06

Figure 20.—Effects of sulfates on ferrocene conditioning at
various fuel-air ratios. Data labels are test modes.


8

Exhaust parameters
co 9 DPM
CO, v GPHC
NOx 4 Extinction
2 © Temperature

a

é

T
ears

CHANGE FROM UNCONDITIONED AVERAGE, pct
®
8

B

0 50 100 150 200 250
CONDITIONING TIME, h

Figure 5.—Effect of ferrocene conditioning on exhaust

parameters for multimode duty cycle.
hydrocarbons).

(GPHC = gas-phase

When conditioning was terminated after 244 h, all the
exhaust emissions were altered. The main objective of this
research program is to reduce DPM emissions from diesel
engines, so the 37-pct reduction after 244 h is considered
a significant result. Because the RDC is a composite of
operating conditions intended to simulate load-haul-dump
operation, this reduction represents the DPM control level
that is achievable in actual mining conditions.

A conspicuous result is the variability of the DPM
changes with conditioning time. The fact that the fuel-air
ratios at 101 and 178 h were 3 pet higher than the uncon-
ditioned, baseline measurements may have contributed to
the variability. The possible influence of increasing sulfate,
caused by the conditioning process, is discussed in a fol-
lowing section. The correlation of both the smoke extin
tion coefficient and CO emissions with DPM agrees with
earlier Bureau results (31, 33).

The increase in CO, and NO, levels plus the reduction
in O,, GPHC, and DPM levels are evidence of enhanced
combustion, consistent with the hypothesis that the con-
ditioning process produced a coating having catalytic oxi-
dation properties.

NO, increases are not desirable because of adverse
health effects. The NO, increase of about 12 pet rep-
resents expected increases in mines. Similar NO, increases
were measured by the Bureau for a barium-based fuel
additive (32).

Steady-State Engine Modes

The experimental results for steady-state engine con-
ditions are organized into two groups—gaseous emissions
and particulate exhaust emissions. Engine conditioning

effects on gaseous emissions are presented in detail here
for two reasons. First, with only one exception, all the
results are consistent with the oxidation catalyst hypothesis.
Second, the changes observed for two toxic gases, CO and
NO,, are documented so that informed judgments about
health effects can be made.

The plots (figs. 6-14) of exhaust emission changes are
similar to those in figure 5, except that the changes are
the differences between conditioned values and values
predicted by regression fits to unconditioned-engine
data. The purpose is to compensate for small fuel-air
ratio variations between unconditioned and conditioned
tests. The procedures are described in appendix C, The
GPHC data (figs. 15-16) were not analyzed by this pro-
cedure because of unsatisfactory regression fits to the
unconditioned-engine data, especially for the measure-
ments at 1,600 r/min.

Gaseous Exhaust Emissions

GPHC concentration measurements are plotted against
fuel-air ratios in figures 15 and 16. Unconditioned-engine
data are plotted for all 14 test modes, but conditioned-
engine measurements are available only for modes 1, 2,
6, 8, 10, and 14.

The measurements at full-rated speed (2,300 r/min)
(fig. 15) show GPHC reductions for all conditioned-engine
data, Therefore, the full-speed data support the idea of
enhanced fuel combustion resulting from the conditioning
process. At 1,600 r/min (fig. 16), however, many meas-
urements show GPHC increases. Two reasons are offered
to explain the discrepancy: (1) the general unreliability
of the FID instrument discussed previously and (2) the
possible influence of prior engine operating conditions.
Tests were always conducted in the order of the mode
number (table 1). Engine operating conditions prior to
beginning the test sequence were variable and were
observed to affect the results for mode 1 (idle) and pos-
sibly for mode 2. However, at the full-speed conditions,
modes 8 through 12, engine and exhaust temperatures
were more consistent because of the consistency estab-
lished by the conduct of the seven prior modes.

Except for mode 2, CO levels (fig. 6) were reduced
after 244 h of engine conditioning. The increase measured
for mode 2 was about 30 ppm, which was 7 pet greater
than the average of levels for unconditioned-engine data.
The increase at 101 h for mode 14 is considered a meas-
urement error because of the obvious inconsistency with
the plots for all the other modes and inconsistency with
DPM reductions that normally correlate closely, especially
at this high fuel-air ratio.

The incidence of both increased and decreased concen-
trations after 244h of conditioning agrees with Bureau
results for barium (37-32). Because CO is an intermediate


18

APPENDIX A._FUEL COMPARISON

A fuel change was required after about 90 h of engine
conditioning. Because the tests were terminated earlier
than planned, the effects of the fuel change were evaluated
by comparing the fuel property analyses and by compar-
ing the exhaust emissions from both fuels. Because of
conflicts with other programs requiring use of the test
facility, these check tests were conducted on a Caterpillar
3304 engine.

The fuel analyses are in table A-1. The fuel used dur-
ing the test period through the initial 90 h is designated
Fuel A. The fuel used after the change is designated
Fuel B.

Table A-1.—Diesel fuel analysis

Refiner! Laboratory”

FuelA FuelB Fuel A Fuel B
‘Aromatics . 42 39 38 at
Sulfur. . 035 4044 «60.36 «0.39
Cetane index . 4 42 42 42
API gravity . 32 3t 33 3t
Flash point . “F.  140- 163130160
Distillation, 90 p °F. 59361460017

TAnalysis conducted by local refiner.
Analysis conducted by independent laboratory.

Fuel B appears to contain slightly more sulfur than
Fuel A. Higher sulfur levels are expected to increase
DPM emissions but, the DPM comparison (fig. A-1)

1.00
*%
:
Z
© took
= IE
3 bE
= [
z
&
who
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07

FUEL-AIR RATIO.

Figure A-1.—DPM emissions for two fuels.

shows no apparent change. A simple explanation is that
the 0.44-pct measurement by the local refiner is too high,
The actual difference in sulfur levels between the two fuels
may be the 0.03 pet measured by the independent labora-
tory. This difference may be too small to have any detect-
able effect on DPM emissions.

A striking characteristic of figure A-1 is the large in-
crease in DPM emissions for full-speed operation com-
pared with operation at 1,200 r/min. This increase was
the result of greater quantities of volatiles on the filter
because of increased levels of GPHC at 1,800 r/min as
verified by the plot of GPHC (fig. A-2).

This conclusion is also verified by the VDPM plots
(fig. A-3), which show that the volatile fraction on the
filters is much higher for 1,800-r/min operation when
similar load modes are compared, such as mode 6 with
mode 8 and mode 5 with mode 9, The point is that
DPM reductions were attributed to ferrocene condition-
ing of the engine, The results (figs. A-2 and A-3) confirm
that these changes were not caused by the fuel change.

The flash point and distillation data in table A-1
indicate that fuel A is slightly more volatile than fuel B.
The data in figures A-2 and A-3 show that this small
volatility difference had no effect on either GPHC or
VDPM emissions.

Finally, it should be noted that all the other exhaust
emissions were examined for differences attributable to
fuel. None were found.

300 7 T ,
KEY
z
250-9 Fuel A
€ 4 Fuel B H
& 1,800 r/min H
% 200}. == 1.200 r/min H
é }
Z 150 H4
8 /
g /
z i aes
Ball : |
Stolohiometic7
. 1 fl . if
° Got 002 008 004 005 006 do7

ee FUEL-AIRRATIO

Figure A-2.—Gas-phase hydrocarbon (GPHC) emissions for
two fuels.


ILLUSTRATIONS—Continued

Page
14. Effect of conditioning time on ratio of extinction coefficient to DPM mass ...........0eeeee eens il

15. Effect of ferrocene conditioning on gas-phase hydrocarbons emissions for steady-state loads
at 2,300 r/min... eee cece eee ee cece s eee eeeteeeueeees bocce ete eneeeneeeeeenees 1

16. Effect of ferrocene conditioning on gas-phase hydrocarbons emissions for steady-state loads
at 1,600 r/min 2.6.6... eee cece een ences . 11
17. Effect of fuel-air ratio on estimated sulfate fraction in DPM 13
18. Effect of fuel-air ratio on estimated sulfate fraction in volatile DPM B
19. Effect of fuel-air ratio on estimated sulfate fraction in solid DPM ... 4
20. Effects of sulfates on ferrocene conditioning at various fuel-air ratios . 14
21, Effect of barium and ferrocene on DPM . sees 15
A-1, DPM emissions for two fuels ......... teeeees 18
A-2, Gas-phase hydrocarbon emissions for two fuels . : 18
A-3, Volatile DPM emissions for two fuels . : 19
B-1. Effect of maintenance concentration of ferrocene on exhaust parameters . 20
B-2. Effect of maintenance concentration of ferrocene on extinction coefficients . . . 20
B-3. Effect of maintenance concentration of ferrocene on gas-phase hydrocarbons . 20
C-1, Adjustment procedures for fuel-air variations ee 21

TABLES

. Modified SAE J1003 emissions test ......
. Research duty cycle modes . .
. Conditioning cycle
}. Oxygen concentration differences between conditioned and unconditioned engine .
A-1, Diesel fuel analysis
D-1. General test data ...... .
D-2. Engine load, sample time, and intake conditions
D-3. Engine conditions
D-4. Particulate parameters
D-5. Gas-phase emissions

PUNE

RRRBREBauY



RESEARCH RECOMMENDATIONS

The Bureau has tested three fuel additives—ferrous
picrate, barium, and ferrocene—to determine their poten-
tial for reducing DPM. Ferrous picrate was ineffective,
so only the Bureau’s earlier results for a barium-based
fuel additive and the ferrocene results are compared in
figure 21. These data show that barium is more effective
than ferrocene at fuel-air ratios greater than about 0.025,
which corresponds to a 50- to 60-pct load at full-rated
speed of 2,300 r/min. For example, barium reduced DPM
by 75 pet at full load, compared with ferrocene, which
reduced DPM by 43 pct. At light loads, on the other
hand, ferrocene reduced DPM by 35 to 45 pct, while bar-
ium was not effective.

1,000 r +
KEY
Fuel treatment

a) © Barium
é © Ferrocene
§ ¥ Ferrocene (idle)
2 £ Unlreated
Z 7 intreated (idle)
&
€ tool 4
5 TOF
8 c
Z sof
§ Mr
z [fo

20 9

10 1 L

° 0.02 0.04 0.06

FUEL-AIR RATIO

Figure 21.—Effect of barium and ferrocene on DPM. Data are
averages.

There is a possibility that the two additives could be
used simultaneously in the same engine. If they are com-
patible, the DPM reductions for the combination may
be greater than either used alone over the full range of
engine operation. Therefore, tests for compatibility and
simultaneous usage could be pursued.

All the Bureau’s tests on additives have been with
high-sulfur fuels (about 0.4 pct fuel sulfur). Therefore, an
area of recommended research is testing both ferrocene
and barium with low-sulfur fuels. Besides alleviating the
problem of increased sulfates caused by the oxidizing
properties of the additives, low-sulfur fuel alone may
reduce DPM by 20 to 25 pet (30).

The water scrubber, used on diesel-powered equipment
in coal mines, may remove DPM more effectively when
ferrocene is used. One study (20) found that DPM con-
centrations decreased when catalytic converters were used
in the exhaust ahead of water scrubbers, because the
converter removed some of the volatiles and made the
soot more wettable. This result is consistent with the fact
that the main effect of ferrocene in the work reported here
was to reduce VDPM. Therefore, it is recommended that
ferrocene be tested with a scrubber-fitted engine to con-
firm this effect.

The results reported here are for only one duty cycle.
It is recommended that the tests be repeated to determine
the maximum emissions reduction possible for other duty
cycles and a range of operating conditions, both steady
state and transient. The test plan should include provision
for determining the optimum engine conditioning proce-
dures such as ferrocene concentration and engine duty
cycle. The optimum additive concentration to maintain
engine conditioning should also be determined.


21

APPENDIX C.—DATA ANALYSIS

Figure C-1 shows all the O, concentrations for mode 6,
including the three baseline measurements (labeled "0")
obtained prior to the conditioning process and the four
measurements (labeled 46, 101, 178, and 244) obtained
during the conditioning of the engine with ferrocene-
treated fuel. The plot shows that after 46 h of condition-
ing O, emissions were similar to those observed for the
unconditioned engine. For the remainder of the condi-
tioning time O, emissions were clearly less than baseline
levels,

Also shown in figure C-1 are two lines. The horizontal
line is the average of the unconditioned engine measure-
ments of O, concentration for mode 6. The second line is
a regression fit of O, concentrations on fuel-air ratio for
all the steady-state test modes conducted prior to the
conditioning process. For O,, the fit is linear with a
correlation coefficient of 0.997 over the entire fuel-air
range from below 0.01 to over 0.05.

The best estimate of ferrocene treatment effects is con-
sidered to be the comparison of conditioned-engine data
with the linear regression line (fig. C-1). For mode 6, the
most significant effect of comparing the data with the
regression line is to reduce the O, concentration changes
attributed to the additive, because the differences between
the values for 101, 178, and 244 h and the fuel-air trend
line are smaller than they would be if calculated from the
average line.

Note that the baseline or unconditioned-engine data are
treated and plotted the same as the conditioned-engine

values. The only difference is that there are usually three
measurements available for the unconditioned engine at
each test mode instead of just the one value available for
conditioned data at each combination of time and mode.
Therefore, at t = Oh the points plotted are averages of
the differences between the three baseline values and the
trend line established by regression analysis of all the
untreated-engine data. These averages are usually differ-
ent from zero and are a measure of data variability or
scatter,

70) . +
2
5 SSP 8 2 _ Average 1
E —S~.-—- — B_Aerage
a
Zz
fo
& eot 4
E
5
G
g 2
rf 5 24
© 58 181 1
é
te
50 .
0.046 0.047 0.048 01049

FUEL-AIR RATIO.

Figure C-1.—Adjustment procedures for fuel-air variations.
Data labels are hours of conditioning time.


24. Sapienza, R. S., T. Butcher, C. Krishna, and J. Gaffney. Soot
Reduction in Diesel Engines by Catalytic Effects. Paper in Symposium
on the Chemistry of Engine Combustion Deposits (Atlanta, GA,
Mar. 29-Apr. 3, 1980). ACS, 1980, 10 pp.

25. Shehukin, E.R, and A. N. Kabanov. Characteristic Features of
the Thermodiffusiophoretic Motion of Aerosol Particles in the Vicin-
ity of a Catalytically Active Surface. J. Aerosol Sci., v. 21, No. 3, 1990,
pp. 409-414,

26. Society of Automotive Engineers (Warrendale, PA). SAE Hand-
book: Engines, Fuels, Lubricants, Emissions, and Noise. V. 3, 1982.

27. Thornburg, D. W. An Investigation of Engine and Test Cell
Operating Conditions on the Effectiveness of Smoke Suppressant Fuel
Additives. M.S. Thesis, Naval Postgraduate Sch., Monterey, CA, 1981,
102 pp.

28. Truex, T. J., W. R. Pierson, and D. E. McKee. Sulfate in Diesel
Exhaust. Environ. Sci, and Technol., v. 14, No. 9, 1980, pp. 1118-1121.

7

29. Walker, B. Improving Diesel Fuel Quality, Combustion, and
Reducing Exhaust Emissions in Engines. Aust. Min. June 1989,
Pp. 62-64.

30. Weaver, C. S., C. Miller, W. A. Johnson, and T. S. Higgins.
Reducing the Sulfur and Aromatic Content of Diesel Fuel: Costs,
Benefits, and Effectiveness for Emissions Control. SAE 860622, 1986,
16 pp.

31. Zeller, H. W. Effects of Barium-Based Additive on Diesel Ex-
haust Particulate. BuMines RI 9090, 1987, 40 pp.

32. ___. Fuel Additive and Engine Operation Effects on Diesel
Soot Emissions. BuMines IC 9238, 1990, 17 pp.

33, Measurement of the Effects of a Fuel Additive on Diesel
Soot Emissions. Paper in Diesels in Underground Mines. BuMines
IC 9141, 1987, pp. 79-93.



Table 4.—Oxygen concentration differences between
conditioned and unconditioned engine
by test mode, parts per million

(Concentration change equals conditioned
minus unconditioned)

Condition-
ing time, 1 2 6 8 10 14 RDC
h

0... 1,300 -1,400 1,000 300-40 -1,200  -500
46 2,500 1,700 800 1,000  -400 -2,400 2,900
101 .... -2,400 -2,400 -4,100 -3,500 -4,500 -5,100 -4,800
178 .... -3,800 -5,200 -4,700 -5,200 -11,000 -7,800 -12,000
244 .... _-2,100 -3,900 -1,800 -4,800 -6,600 -5,600 -6,700

RDC Research duty cycle.

Mass balances for the unconditioned-engine test data
(t = Oh in table 4) accounted for all the O,, within
+1 pet, into and out of the engine. The exhaust compo-
nents included in the mass balance were O,, CO,, NO,,
H,0, and SO,. In the case of conditioned-engine data,
however, the O, mass balances did not account for all the
O, into the engine. The largest imbalance was for the
RDC at 178 h, for which 9 pet of the intake O, could not
be accounted for in the exhaust. Instrument response time
may have contributed to the discrepancy because simple
averages were used for the 8-min transient test cycle
(RDC). The next largest discrepancy was for mode 14 at
178 h where 6 pct of the O, into the engine was not
accounted for. There is no explanation for this result.

Particulate

Three types of particulate are discussed in this section.
The total weight gain of the filter deposits is termed DPM.
The material remaining on the filter after treatment for
24h in a 400° F vacuum oven is called the solid diesel
particulate matter (SDPM). The fraction removed by the
oven treatment is the volatile diesel particulate matter
(VDPM) and is intended to represent an estimate of
organic extractables or the soluble organic fraction (SOF).

Because the vacuum oven process also removes most
sulfates (77), the SOF is overestimated.

The relative or percent DPM changes (fig. 10) show
that DPM emissions were already reduced at 46h for
modes 2, 6, 8, and 14, After 178 h DPM emissions were
reduced for all modes. At 244h the reductions were
between 35 and 45 pct for modes 1, 2, and 14. These
maximum reductions for steady-state conditions are
equivalent to the reduction of 37 pet for the RDC at 244 h
(fig. 5).

‘Comparison of the DPM concentration changes (fig. 11)
with those for CO (fig. 6) show close agreement, especially
for modes 6 and 14. This agreement implies that both
emissions are affected similarly by ferrocene. This result
is also consistent with a comparable relationship observed
for the RDC (fig. 5).

SDPM and VDPM data (fig. 12) for both uncondi-
tioned and conditioned tests are available only for modes
1, 2, 8, and 10, Although not determined, measurement
error is the most likely explanation for the large increase
recorded for mode 10 at 46 h.

After 244 h the SDPM was not substantially different
from the range of values measured for the unconditioned
engine at t = Oh. These data confirm that only the mag-
nitude of the SDPM was unchanged. Conclusions about
composition changes—the relative levels of carbon and
sulfates—cannot be made.

If the magnitude of the SDPM was unaffected by the
conditioning process, then the DPM reductions were
probably caused by reduced VDPM. This inference is
verified in figure 13, which shows VDPM reductions after
178 h for all test modes and substantial reductions, more
than 50 pet, after 244 h.

The ratios of extinction coefficients to DPM concen-
trations (fig. 14) increase with engine conditioning time.
Earlier Bureau results showed that extinction response
is mainly a function of SDPM (31, 33). Therefore, the
increasing ratios in figure 14 are consistent with the
composition changes caused by VDPM (SOF) reductions
31, 33).

DISCUSSION AND INTERPRETATION OF EXPERIMENTAL RESULTS

Experimental observations, noted in previous sections,
indicate that engine conditioning with ferrocene-treated
fuel produced a red coating of ferric oxide on combustion
surfaces and caused exhaust emissions changes for both
transient (RDC) and steady-state engine operating con-
ditions. The discussions in this section are intended to
provide additional support for the oxidation catalyst hy-
pothesis by proposing mechanisms for the observed emis-
sions changes and by estimating the expected effects of
sulfate emissions.

PROPOSED MECHANISMS INVOLVING
CATALYTIC OXIDATION SURFACES

According to Kamimoto, one source of DPM is wall
quenching of combustion flames (12). He concluded that
“flame impingement has contradictory effects on diesel
combustion. It enhances mixing and promotes utilization
of high density air (oxygen) near the wall, but at the same
time causes flame quenching which is one of the main
origins of soot emission."


KEY
cocees0000 Diluted exhaust
sorceseseesese Dilution air
weno Exhaust sample orifice

—~— Gas emissions sample
Raw exhaust —

Signal Data
condition|COroller]  iggger
Particulate
ynamometer, filter
Fuel
tank|
Pump
++ {Opacity| Outside
Computer ee
CO CO
GPHC O02
NOx
S Dilution air

Control room Test cell Emissions room

Figure 1.—Diesel engine testing facility.

Sample
Activated @ @ orifice
Primary —e) ‘charcoal B

ail and HEPA

air ‘iter Ure Eyos

—+ Exhaust

Togas ‘Smoke
analyzers opacity
meter

Engine

Universal dynamometer

KEY ‘High
- volume
HEPA High-efficiency particulate air pump

LFE Laminar flow element
PDP Positive displacement pump
® Pressure

@ Pressure differential

@

‘Temperature

Figure 2.—Alir Intake and dilution systems.



Table D-3.—Engine conditions

Engine Brake Exhaust Engine Brake Exhaust
Fuel volume Fuel-to- specific temper- Fuel, Power, volume Fuel-to- specific _ temper-
Mode! rate, Power, flow, air fuel con- ature, Mode! rate, bhp flow, air fuelcon- —_— ature,
Ib/n bhp cfm ratio sumption, °F Ib/h cfm ratio sumpti “
Ib/hp-h Ib/hp-h
MASOO1 MAS102
1. 26 11 69 0.0084 2.40 178 (cont):
2 64 23 149 .0097 2.78 240 9... 26.9 59.1 190 0.0320 0.45 727
98 158 144 0154 62 338 10.. 204 393 196 0235 52 561
142 318 139 0231 45 471 11... 148 197 203 0165 75 426
19.4 47.7 134 0327 Al 640 12... 10.7 43 207 0117 2.48 335
269 64.3 128 0475 a2 930 27 44 69 = 0088 2.48 180
24 10 69 0080 2.38 191 27.1 604 117 052345 1,018
355 80.1 © 185 0434 a4 968 175 364 «= 131030248. 612
269 60.2 190 .0320 45 729
20.3 40.1 196 0233 50 559 26 1.0 69 0084 _2.64 186
14.4 20.0 203 0161 72 420 64 24 148 = .0098 2.99 249
104 43 208 0113 2.40 328 100 158 143 0158 63 348
25 11 69 0083 2.33 178 144 317 189028645 483
27.8 609 117 0538 46 1,031 197 476 1338 ©0335 1 652
174 371 132 .0300 AT 622 273 645 127 0484 a2 955
25 1.0 69 = 0083 2.54 200
26 10 70 0084 2.54 176 35.6 786 181 0444 45 989
62 22 148 .0094 2.76 242 268 59.1 191031845 743
9.9 158 144 0155 62 339 205 394 197 0236 52 873
142 317 138 0233 45 476 148 196 204 0164 «9.76 431
19.4 476 133 .0330 at 649 10.7 41 208 = .0117_— 2.61 341
265 63.6 129 0466 A2 920 26 1.0 70 0084 2.64 184
25 10 69 0081 2.49 193 279 592 118 0536 47 1,042
35.1 78.9 © 184 0431 45 963 177 360 «131 «030749 655
265 59.0 190 0316 45 724
202 393 196 0233 3 563 28 1.0 69 = 0093 _2.84 NA
144 196 202 0161 73 426 68 22 149 0108 3.15 NA
104 41 207 0113 2.51 334 104 158 145 0162 66 NA
26 10 70 .0083 2.56 180 148 317 © 14002407 NA
27.3 60.1 117 0527 451,028 200 476 134 0337 42 NA
17.2 363 © 132 0294 47 620 27.6 645 129 6.048543 NA
28 1.0 72.0089 _2.81 NA
26 10 69 0085 2.62 185 367 80.9 186 0446 45 NA
61 22 148 0093 2.80 245 27.1 591 193 0319.46 NA
98 158 144 0154 62 343 208 394 197 0239 53 NA
143° 318 © 139 0234 45 482 150 196 204 0167 77 NA
195 476 133 0331 A 659 W441 2080121268 NA
265 629 129 0467 a2 935 31 1.0 68 = «0101 3.12 NA
24 10 69 .0080 2.43 202 28.1 598 118 0539 47 NA
34.70 775 187 0421 5 964 18.1 36.9 133 0308 49 NA
26.7 59.1 191 0317 45 730
20.2 39.3 197 .0233 51 563 27 1.0 69 0088: 278 183
144 196 203 0161 73 425 62 24 148 = 0096 2.95 245
104 44 207 0114 2.39 333 95 158 143 0151 60 347
26 14 69 0087 2.41 180 145 317 138028846 482
26.1 587 (117 .0505 45 978 199 476 133 033942. 654
175 365 = 132 .0301 48 628 274 643 «127048743 965
25 1.0 69 ©0081 _2.44 203
27° 10 70 0088 2.60 181 356 798 184 0438 45 997
2 65 23 148 0100 2.84 244 26.7 59.1 199 031945 742
3 10.1 158 143 0159 64 340 204 394 195 0237 52 573
4.. 146 31.7 139 0238 46 476 146 19.7 201 0164 74 435
5... 197 476 133 0334 A 643 103 37 206 0114 277 339
6... 268 641 128 0474 42 922 25 9 69 = 0081 2.74 184
7. 25 141 69 0082 2.32 193 27.0 589 117 ©0523 AG 988
8... 357 793 186 0434 45 958 173363 132020648 625

NA_ Not available,
RDC Research duty cycle.

{Data sets MASOO1 and MASOO2 are for fuel without ferrocene; MAS101, MAS102, MAS103, MAS104, and MAS105 are for fuel with the
conditioning concentration of ferrocene.


EFFECTIVENESS OF IRON-BASED FUEL ADDITIVES
FOR DIESEL SOOT CONTROL

By H. William Zeller’ and T. E. Westphal?

ABSTRACT

The U.S. Bureau of Mines evaluated the effects of two iron-based fuel additives on diesel particulate
matter (DPM) emissions. The 5.6-L, six-cylinder test engine is typical of engines used in underground
mines. One additive, ferrous picrate, did not measurably affect exhaust emissions, This report is mainly
about a ferrocene-based additive that reduced DPM between 4 and 45 pct, depending on engine
operating conditions. The report concludes that the DPM reductions were caused by the catalytic
oxidation properties of a ferric oxide coating that developed inside the engine’s combustion chamber.
The ferric oxide coating also decreased gas-phase hydrocarbons and O,, but it increased CO, and NO,.
The increase in NO,, of about 12 pct, is considered the only adverse effect of the ferrocene-based fuel
additive. The results suggest that the effectiveness of ferrocene was partially offset by increased sulfates
because of the high-sulfur fuel used. Recommendations for continuing fuel additive research are
presented.

\physical scientist.
?Mechanical engineer (now with Ford Motor Company, Dearborn, MI).
‘Twin Cities Research Center, U.S. Bureau of Mines, Minneapolis, MN.


atm
bhp
cfm
cm

°F

ft-lb

gal

h/d

hp

UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT

atmosphere, standard
brake horsepower
cubic foot per minute
centimeter

degree Fahrenheit
foot

foot pound

gallon

hour

hour per day
horsepower

inch

liter

Ib/h
Ib/hp-h
mg
mg/m?
min
mm Hg
Oz

pet
ppm

r/min

wt pet

pound per hour
pound per horsepower-hour
milligram

milligram per cubic meter
minute

millimeter of mercury
ounce

percent

part per million

revolution per minute
second

weight percent



Because wall quenching increases DPM emissions, it
follows that changes in wall properties, such as the for-
mation of a catalytically active coating, may have major
effects on emissions. For example, catalytically enhanced
combustion at the chamber wall may raise wall tempera-
tures sufficiently to mitigate flame-quenching effects and
reduce unburned hydrocarbons in the exhaust.

There is also at least one mechanism to account for the
reduction of carbon formed in the gas phase. Ambs (1)
showed that up to 40 pet of exhaust particulates spend
some time on combustion chamber surfaces. Specifically,
Ambs’ model describes how carbon particles are deposited
thermophoretically on the walls and then are reentrained
into the exhaust stream.

Shchukin (25) has shown that under some conditions,
such as SO, oxidation to SO,, thermophoretic forces
caused by the high wall temperatures, because of cata-
lytically active surfaces, may repel particles from the walls.
The particle size of soot carbon, which remains suspended
in the gas phase, is smaller and more easily oxidized than
the large agglomerates entrained from wall deposits.

Cooper (5) describes mechanisms that can enhance
oxidation of this gas-phase carbon through the formation
of active oxidizing species such as NO,. The catalytic
ferric oxide enriches the concentration of NO, in a zone
near the wall. Soot arriving in this zone will adsorb NO,,
which oxidizes C to CO, which may be further oxidized to
CO,. This mechanism is consistent with the NO, increases
depicted in figure 7.

EFFECT OF SULFATES ON PARTICULATE

Although the contribution of sulfates to DPM was not
measured in this study, it can be estimated. There is gen-
eral agreement that 1 to 3 pet of the fuel sulfur is con-
verted to sulfates in the exhaust from uncatalyzed diesel
engines (2,13). Truex proposed that this conversion takes
place on the surface of exhaust carbon in diesel engines
(28).

Data by Baranescu (2) indicate that the conversion rate
depends on engine load (temperature) and is the basis for
assuming a SO, to SO, conversion function that increases
linearly from 1 pet at fuel-air ratios of 0.01 to 3 pet at a
fuel-air ratio of 0.06.

Halsall (12) observed that about 70 pct of the sulfates
formed are removed by vacuum oven sublimation, leaving
30 pet of the sulfates on the filter.

Based on the fuel sulfur level of 0.4 pct, the assumed
linear conversion function, and on Halsall’s measurements,
estimated sulfate contributions to DPM, VDPM, and
SDPM are shown for the unconditioned engine in fig-
ures 17 through 19. Even though only 1 to 3 pet of the
fuel sulfur is converted to sulfates in the exhaust emissions,

13

the sulfate contribution to DPM can be substantial,
especially at fucl-air ratios between 0.02 and 0.04 (fig. 17).

The high sulfate levels in this range of fuel-air ratios
are caused by the manner in which soot carbon and
sulfates change with fuel-air ratio. Sulfates increase more
rapidly than carbon at low fuel-air ratios. Therefore, the
ratio of sulfates to carbon increases rapidly. At fuel-air
ratios greater than about 0.04, carbon levels increase much
more rapidly than sulfate levels; therefore, the significance
of the sulfates is reduced at high fuel-air ratios. The net
result is that modes 8 (20 pet sulfate) and 10 (12 pet
sulfate) are most affected and mode 2 (2 pet sulfate),
which has a low fuel-air ratio of 0.01, is the least affected.

At high fuel-air ratios, a surprising result is that sul-
fates can potentially account for most of the VDPM
(fig. 18) as measured by the vacuum oven method. On the
other hand, the estimates (fig. 19) show that sulfates

26 7 T T T
KEY
Engine speed

3 20+ o Ide 1
& © 1,800 r/min
Zz & 2,300 r/min
6
2 ist 4
Q /
Fa
we toh 4
g
¢ °
B sb 4

a A 1 1 A

° oor 002 003 0.04 005 008

FUEL-AIR RATIO.

Figure 17.—Effect of fuel-air ratio on estimated sulfate fraction
in DPM. Data labels are test modes.

200, T r r 1
KEY 3

3 100 Engine speed q
2 Ide
% 50F —o 1,60007min
5 4 2,300 r/min 5
2
E 20
B
& tok 4
3
3
yos
z 12%
g 7
3 28

2

1 A . A f

0 or 0.02 0.03 0.08 0.05
ee FUEL-AIR RATIO.

Figure 18.—Effect of fuel sstimated sulfate fraction



OBJECTIVES

The main objective of these investigations is to find
the potential of fuel additives to reduce DPM when used
in indirect injection engines representative of the types
used in underground mines. This objective has been
accomplished,

A second objective is to determine how to use the
additives most effectively. Because ferrous picrate, at
two different concentrations in the fuel, had no meas-
urable effect on exhaust emissions, the tests were ter-
minated. Ferrocene was effective at the manufacturer's

recommended concentration levels, but the work was
terminated prematurely because of equipment problems.

A third objective is to identify undesirable effects
caused by the additives such as reduced engine perform-
ance, reduced engine service life, and increases in toxic
exhaust emissions. This objective has been partially
completed for ferrocene because changes in some toxic
emissions were measured.

The main purpose of this study is to justify the con-
clusions that ferrocene-treated fuel produced a catalytic
ferric oxide coating on portions of the test engine’s com-
bustion surfaces, that this coating enhanced combustion,
and that it reduced DPM.

ACKNOWLEDGMENTS

The accomplishment of the long-duration tests dis-
cussed in this report required considerable cooperation
among the individuals who operate the diesel engine test
facility. The authors acknowledge the following people

for their efforts to complete the program within the con-
straint of available time: C. F. Anderson, A. M. Benning,
C. G. Cordova, T. L. Hillman, G. R. Vandenbos, and M. J.
Vogel.

APPARATUS AND PROCEDURES

The equipment and procedures used in this investi-
gation (fig. 1) are described only briefly here. More
detailed descriptions of the engine controls, dilution tun-
nel, DPM collection, and gas emissions measurements are
in other Bureau reports (7, 37).

ENGINE

A naturally aspirated, indirect injection, four stroke
Deutz F6L 912W diesel engine was used. The engine is
rated for 83 hp at 2,300 r/min. An eddy-current dyna-
mometer supplied the loads to the test engine. Speed and
load were controlled within +1 r/min and +1 ft-lb, re-
spectively. A mass metering system, with an accuracy of
+0.5 pet, measured fuel consumption. The air supply
system (fig. 2) maintained the engine’s intake manifold at
conditions equivalent to Society of Automotive Engineers’
(SAE’s) standards (76° F, 1 atm) for power measurements
(26). DPM and other emission concentrations presented
in this report are adjusted to these SAE standard
conditions.

PARTICULATE MEASUREMENT

The dilution system (fig. 2) provided a representative
sample of the exhaust for DPM samples. The diesel par-
ticulates were collected on 8- by 10-in fluorocarbon-
coated, glass-fiber filters. Temperature and pressure
across the sample orifice were measured and used to cal
culate dilution ratios. ‘The dilution was also checked from

measurements of nitrogen oxides (NO,) in the raw and the
diluted exhaust. An in-line diesel exhaust smokemeter
measured smoke opacity.

GAS EMISSIONS MEASUREMENT

Five gaseous exhaust components were measured
(fig. 1). The sample for gas-phase measurements was ex-
tracted from the raw exhaust at a point near the dilution
tunnel sampling point and was transported to the gas emis-
sions measuring instruments through a 25-ft line heated
to 400° F. CO, and CO were measured with nondisper-
sive, infrared analyzers. O, was measured with an instru-
ment with a polarographic sensor. NO, were measured
with chemiluminescence analyzers. Measurements of
specific nitrogen oxides were not obtained.

Gas-phase hydrocarbons (GPHC) were measured with
a flame ionization detector (FID). FID responds only to
those hydrocarbons that manage to penetrate the heated
sampling line and the particulate filter just ahead of the
instrument. Hydrocarbons with boiling points less than
400° F are presumed to penetrate to the FID, but low-
volatile components, such as oils with boiling points
greater than 600° F, are not believed to penetrate to the
FID at all. Substances with boiling points between 400°
and 600° F, such as many polycyclic aromatic hydrocar-
bons and paraffin fuel components, may only be partially
measured.

Preliminary experiments (unpublished) showed that FID
response accounts for less than 35 pct of diesel fuel sample


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Figure A-3.—Volatile DPM (VDPM) emissions for two fuels.


RI| 9438 REPORT OF INVESTIGATIONS /1992

Effectiveness of Iron-Based Fuel Additives
for Diesel Soot Control

By H. William Zeller and T. E. Westphal

UNITED STATES DEPARTMENT OF THE INTERIOR —

BUREAU OF MINES —


The first two baseline sets were conducted using fuel
without ferrocene. These tests are identified by the
numerical suffixes 001 and 002 in appendix D. The third
baseline set was with fuel treated with the maintenance
concentration of 1 part additive to 1,280 parts fuel. These
data have the numerical suffix 101 in appendix D. The
purpose was to measure the effect, if any, of this low
concentration on engine performance and exhaust emis-
sions before the additive conditioning process began.

Engine Conditioning

The ferric oxide coating on the engine’s combustion
surfaces was formed in this phase by using the ferrocene-
based additive in the fuel at the conditioning concentration
of 1 part additive to 320 parts fuel (20 oz of additive in
50 gal of fuel).

Using the special conditioning cycle (table 3), the
engine was operated 8 to 10 h/d. ‘The engine intake was
pressurized to about 50 in of water above local atmos-
pheric pressure to minimize DPM emissions and to short-
en the time necessary to condition the engine.

Table 3.—Conditioning cycle

Speed, Load, Time,
r/min pet min
2,070 80 30
2,070 90 30
2,070 100 30
2,300 400 30
2,300 90 30
2,300 80 30

During the conditioning cycle, CO and opacity were
continuously monitored to detect any effects of the con-
ditioning process. Periodically the engine was run with the
maintenance concentration of the additive to check on the
emissions changes. The procedure was the same as that
in the baseline phase except that only about half the test
modes were checked. These were modes 1, 2, 6, 8, 10,
14, and the RDC. Because of the premature termination
of the conditioning process, these data are the basis for
evaluating the effects of the conditioning process and
are labeled with the suffixes 102, 103, 104, and 105 in
appendix D.

Data Analysis

The intent was to repeat the tests conducted during the
initial baselining phase and compare the emission meas-
urements to evaluate additive effects. In the original plan,
data from all 14 steady-state conditions (table 1) and the
RDC were to be analyzed for exhaust emissions changes
for comparison with the initial baseline measurements.

Unfortunately, engine conditioning was terminated af-
ter 244 h because of dynamometer failure. Consequently,
the analysis was restricted to the six steady-state modes
and the RDC, for which data were obtained during the
conditioning phase. These seven modes are considered
adequate and representative because they include light-,
medium-, and full-load tests; idle, peak-torque, and
full-rated speed tests; two intake conditions; and the
RDG, which is a combination of many engine operating
conditions,

The possibility that a fuel change at 90 h was respon-
sible for the effects observed on exhaust properties was
eliminated by the following procedures. First, the exhaust
data were examined for any abrupt or step-like changes in
levels occurring at the time of the fuel change. None were
found. Second, both fuels were run in another engine, a
Caterpillar 3304, Analyses of the exhaust properties for
the Caterpillar engine showed no detectable differences
between the two fuels (appendix A). Third, fuel proper-
ties were also examined for differences. The data (ap-
pendix A) show differences considered too small to
produce the exhaust property effects observed. Further-
more, the differences are considered to be within the error
range of the property test procedures. Because all the fuel
came from the same supplier, the similarity between the
two fuel lots was anticipated,

Another potential problem was that all the data ob-
tained during the conditioning process were from fuel
containing the maintenance concentration of the ferrocene
additive. However, no effect of the low maintenance
concentration was detected in the baseline data involving
tests with and without ferrocene (appendix B). Because
no noticeable differences were attributable to additive in
the fuel, all the baseline data are considered equivalent.
In the analyses that follow, the unconditioned-engine data
(suffixes 001, 002, and 101 in appendix D) are usually
combined to provide an average baseline value against
which the conditioned-engine data are compared.

EXPERIMENTAL RESULTS FOR FERROUS PICRATE

The ferrous picrate concentrations used were 0.033 and
0.33 wt pet of the commercial product in the fuel. Based
on information from the distributor, the concentration of
the active ingredient, ferrous picrate, in the fuel at the
recommended concentration (0.033 wt pct) is estimated
to be about 0.5 ppm.

Ferrous picrate had no effect on DPM emissions from
the Deutz engine (fig. 3). Furthermore, the use of the
additive had no effect on CO, CO,, O,, hydrocarbons, and
NO,. The measurements plotted in figure 4 for CO are
representative of those obtained for all the gaseous
emissions. Ferrous picrate is said to burn out engine


injected at the sample line intake. Also, the response of
the instrument may depend on the molecular weight or

carbon number of compounds (6). Methane was used in
these experiments to calibrate the FID.

EXPERIMENTAL APPROACH

TEST PLAN FOR FERROUS PICRATE

The test plan for ferrous picrate called for initial
screening tests at steady-state engine conditions to meas-
ure effects of the additive on DPM emissions for a wide
range of fuel-air ratios at different engine speeds and
loads. The test conditions included engine operation at
idle and three additional speeds—peak torque speed of
about 1,600 r/min, 1,830 r/min (80 pct of rated speed),
and at the rated speed of 2,300 r/min. Engine loads
included 50, 75, 90, and 100 pct of full torque at the
selected speeds.

The plan also called for the screening tests to be con-
ducted at the recommended concentration in diesel fuel
of 1 part additive to 3,000 parts fuel, or 0.033 wt pct. If
the preliminary screening tests showed that the additive
had any potential for reducing DPM, more extensive test-
ing was planned.

When no effects on exhaust emissions were measured,
1 set of additional tests was conducted using an additive
concentration 10 times that recommended, or 1 part addi-
tive to 300 parts fuel. When no emissions effects were
observed, the tests on ferrous picrate were terminated.

TEST PLAN FOR FERROCENE

This additive requires a period of engine "conditioning"
to develop the catalytic coating inside the engine (16).
The conditioning process requires engine operation with
ferrocene-treated fuel at a concentration about four times
greater than the "maintenance" concentration recom-
mended for maintaining the coating in normal use. Be-
cause of the engine conditioning required, the test plan for
ferrocene was much more extensive than that for ferrous
picrate. The plan called for the following phases: baseline
measurements to establish initial engine emissions levels,
engine conditioning to develop the ferric oxide coating,
and repetition of the baseline tests to measure the effects
of engine conditioning with ferrocene,

Baseline Tests

This phase established the baseline emissions for the
unconditioned engine. Each set of baseline measurements
consisted of a modified SAE J1003 (26, pp. 25.25-25.26)
emissions series (table 1) and the research duty cycle
(RDC) (table 2). The results of the SAE J1349 power

curve test (26, pp. 24.09-24.10) were used to define the
actual torque loadings used.

Table 1.—Modified SAE J1003 emissions
test

(Time for each mode was 20 min)

Speed, Load, Air in-
Mode! t/min pet take den-
sity, pot?
1. 750 oO 0.97
2 1,600 2 7
3 1,600 25 7
4 1,600 50 97
5 1,600 75 7
6 1,600 100 7
7 750 i) 7
8 2,300 100 97
2,300 75 7
2,300 50 97
2,300 25 97
2,300 2 a7
750 oO 7
1,600 100 87

Modes 1 through 13 comprise the SAE
J1003, 13:mode sequence, and modes 1
through 14 comprise the modified SAE
J1003 test sequence.

*Percent of density at SAE standard
conditions.

Table 2.Research duty cycle modes

Applied ‘Speed,! Load,
time, pet pet
s
30 100 50
30 100 100
30 25 25
30 100 50
30 100 100
30 Q 0
30 ¢) 100
60 °
30 (9) 100
30 100 400
30 25 25
60 ie) 100
60 io) 0
1Full g} is rated at 2,300 r/min.

Engine idle.
3Engine at peak torque speed,
about 1,600 r/min for Deutz engine,


Table D-5.—Gas-phase emissions, parts per million

HC NO, CO _CO, O, Mode! HC NO, CO CO, Oo,
MAS102 (cont):
59 290 240 19,800 188,000 9 . 56 560 140 71,300 113,000
104 210 360 22,400 177,000 75 400 170 54,000 138,000
85 340 190 35,600 157,000 72 270 230 37,500 162,000
83 540 150 53,200 136,000 99 170 340 26,600 178,000
78 720 140 74,000 110,000 60 300 210 19,300 189,000
78 680 350 106,200 65,000 70 670 900 120,000 45,000
65 260 210 18,500 193,000 46 500 150 55,100 129,000
65 570 210 98,500 77,000
76 510 160 72,200 115,000 71 340 250 20,900 183,000
83 370 170 52,900 142,000 122 240 380 24,000 179,000
82 250 230 36,900 162,000 87 350 190 35,700 161,000
100 160 320 26,100 173,000 69 530 140 52,600 135,000
65 290 240 19,600 179,000 57 720 130 72,200 108,000
327 620 1,350 121,500 42,000 76 720 400 109,400 55,000
71 40 180 54,100 126,000 57 310 200 18,900 187,000
54 630 240-=—«100,800 68,000
54 300 230 19,800 186,000 58 520 160 72,000 108,000
94 220 330 22,700 183,000 76 400 180 54,000 134,000
79 350 180 36,400 163,000 79 270 240 37,600 157,000
7 530 150 53,900 138,000 108 170 360 26,500 174,000
75 710 150 75,800 108,000 75 310 240 19,400 185,000
7 710 380 106,600 65,000 104 640 1,460 121,000 36,000
52 280 200 19,000 187,000 42 480 210 56,600 119,000
62 610 220 ‘98,700 76,000
70 520 160 71,700 111,000 59 320 NA 21,300 179,000
81 oO 170 53,500 138,000 132 240 NA 24,200 174,000
82 240 230 37,700 161,000 99 330 NA 36,100 156,000
101 160 320 26,700 176,000 85 510 NA 54,200 131,000
59 310 220 19,800 186,000 65 710 NA 75,100 102,000
82 640 1,160 121,200 46,000 69 710 NA 112,500 52,000
59 460 170 53,300 127,000 53 290 NA 19,100 177,000
53 680 NA 103,800 68,000
62 290 230 19,900 185,000 57 570 NA 73,600 102,000
96 220 320 22,500 182,000 68 420 NA 55,700 126,000
80 340 170 35,700 162,000 73 250 «=NA — 33,600 131,000
76 530 140 53,400 137,000 119 180 NA 27,700 163,000
82 730 140 75,100 107,000 81 290 NA 20,800 172,000
90 710 370 104,800 63,000 71 630 NA 125,600 33,000
68 270 190 19,000 187,000 48 500 NA 58,100 111,000
67 560 210 95,500 77,000
74 490 160 71,600 110,000 54 370 250 21,800 182,000
o1 350 190 52,900 137,000 100 260 350 (24,200 178,000
102 240 260 37,500 160,000 87 400 180 37,000 159,000
113 160 340 26,600 176,000 71 600 140 53,700 136,000
66 300 220 20,200 186,000 72 830 140 75,400 107,000
73 660 740 118,300 52,000 84 810 420 113,400 56,000
57 470 200 54,700 126,000 55 310 200 19,600 184,000
56 680 210 103,900 70,000
1. 64 280 230 20,000 187,000 57 570 130 73,400 109,000
2. 102 220 340 23,200 182,000 62 440 150 55,500 132,000
3. 75 330 180 35,100 164,000 78 280 230 38,800 155,000
4. 67 500 150 51,700 141,000 117 180 350 27,000 172,000
5. 59 710 130 71,700 112,000 66 320 230 20,500 181,000
6. 6S 750 320 107,300 63,000 95 680 620 119,000 43,000
7. 49 290 170 18,500 190,000 50 510 NA 56,900 121,000
8. 52 650 200 ‘98,000 75,000

NA Not available.

RDC Research duty cycle.

‘Data sets MASOO1 and MASO02 are for fuel without ferrocene; MAS101, MAS102, MAS103, MAS104, and MAS105 are for fuel with the
conditioning concentration of ferrocene,


Table D-4.—Particulate parameters

Filter Volatile Exhaust DPM — Extinction Filter Volatile Exhaust DPM — Extinction
Mode? DPM (VDPM) dilution concen-  coeffi- Mode? DPM (VDPM) dilution concen-  coeffi-
weight, weight, ratio tration, —_cient, weight, weight, ratio tration, —_cient,
mg mg mg/m? cm? mg mg mg/m? em?
MASO01: MAS102 (cont.):

1. 197 11.9 20 30 0.09 9. . NA NA 15 NA 0.28
647 44.4 18 95 21 42.4 57 19 68 26
510 32.9 19 78 24 NA NA 15 NA 22
439 29.3 19 86 29 NA NA 15 NA at
51.2 NA 19 83 38 NA NA 19 NA 06
46.5 NA 2t 339 2.69 450 355 23 637 5.28
13.3 7.3 20 21 08 274 55 2t 87 55
28.8 NA 18 124 80
39.8 NA 18 37 33 16.3 93 22 28 05
396 19 7 68 31 508 367 021 84 17
478 30.4 7 79 26 NA NA 18 NA 21
58.2 © 37.6 16 76 26 NA NA 18 NA 25
159 8.2 20 25 41 NA NA 7 NA 34
67.9 NA 22 909 7.36 69.4 28 9 24 344 2.67
38.1 NA 19 110 73 NA NA 21 NA 07

40.2 33 22 130 86
18.8 NA 24 30 02 NA NA 16 NA 32
60.0 39.6 20 94 15 445 0 217d 74 28
486 30.9 20 80 18 NA NA 7 NA 23
468 8627 21 87 22 NA NA 17 NA 24
52.3 NA 21 93 36 NA NA at NA 06
52.5 NA 22-364 2.65 56.9 0 25 867 7.16
12.9 6.4 24 2t 02 36.5 0 23 123 80
39.5 NA 21 139 76
34.3 NA 20 57 22 172 64 19 26 05
36.0 16.9 20 70 20 484 0 275 19 73 18
47.2 287 19 74 15 NA NA 16 NA 23
532 33.3 18 79 15 NA NA 16 NA 27
14.8 75 2 24 02 NA NA 18 NA 38
56.2 NA 23 804 6.27 474 16 0 (t 399 3.03
33.3 NA 2 105 59 NA NA 18 NA 06
44.2 37 20 132 89
204 13.6 20 32 03 NA NA 14 NA 30
595 40.9 19 90 15 330 011 19 51 a
45.4 NA 19 73 17 NA NA 13 NA 23
474 NA 20 80 23 NA NA 15 NA 22
507 18.5 21 88 36 NA NA 18 NA 08
60.0 Cy) 22 373 2.89 62.5 0 22 833 8.20
14.2 73 20 23 05 36.0 0 20 110 79
35.6 46 20 123 72
372 10.1 19 60 28 14.0 52 19 20 1
423 186 19 66 23 375 19.3 18 54 a2
502 31.9 18 88 20 NA NA 16 NA 14
60.1 39.8 18 85 19 NA NA 15 NA 19
179 105 20 28 06 NA NA 15 NA 31
42.6 0 22 549 4.38 15 4 20 380 2.99
414 4 24 125 76 NA NA 18 NA 04
42.5 1.4 19 122 82
26.2 3.9 20 42 06 NA NA 14 NA 25
54.7 2 19 87 20 32.9 87 18 49 20
NA NA 7 NA 23 NA NA 15 NA 13
NA NA 7 NA 29 NA NA 15 NA 10
NA NA 15 NA 36 NA NA 18 NA -01
97.5 20 22 341 2.39 35.1 NA at 440 4.26
NA 19 NA 06 24.8 1 20 72 A
sees 403 44 20 126 85
Not available.

ROC Research duty cycle.
‘Data sets MASOO1 and MASOO2 are for fuel without ferrocene; MAS101, MAS102, MAS103, MAS104, and MAS105 are for fuel with the
conditioning concentration of ferrocene.


INTRODUCTION

PROBLEM

Diesel-powered equipment is widely used in under-
ground mining because of its high productivity and flex-
ibility compared with electric-powered equipment. Unfor-
tunately, diesel engines emit particulates consisting of
carbonaceous agglomerates, adsorbed organic compounds,
and other substances such as sulfates and metals. Al-
though diesel particulate matter (DPM) levels are not
specifically regulated in underground mines, DPM adds
to the general dust level.

To help mine operators comply with dust standards and
to address concerns about potential occupational health
problems (22)? arising from exposure to DPM emissions,
the U.S. Bureau of Mines is conducting research to
develop improved DPM control methods. Much of the
research has been on the evaluation of the diesel par-
ticulate filter (3), but to provide the mining industry with
alternatives the Bureau is also evaluating fuel additives.

FUEL ADDITIVES
Background

The work presented here is a continuation of fuel-
additive research initially reported by the Bureau in 1987
(32). These earlier investigations were on a postflame,
barium-based additive, and they confirmed claims that
additives can reduce DPM emissions (3-33). Although
the barium additive was not effective at light engine loads,
the DPM reductions measured were sufficient to encour-
age further additive testing.

The selection of additional additives involved con-
sideration of the following requirements: to broaden the
scope of the research by testing other additive categories,
such as flame-type; to evaluate only additives for which
emissions reductions have been documented; and to in-
clude only additives expected to have negligible adverse
health effects when emitted in the engine exhaust. Certain
iron-based compounds met all three of these requirements.

A particular attraction of iron-based additives is the
lack of any documented adverse health effects caused by
iron compounds in the exhaust. For example, Klarman
(4) did not identify any health-related problems attrib-
utable to iron-based fuel additives.

Tron-based fuel additives have been shown to reduce
DPM emissions from diesel engines (18-19). Related
research on turbines (17, 27) and laboratory simulations

Italic numbers in parentheses refer to items in the list of references
preceding the appendixes at the end of this report.

using various flame geometries (4, 15) showed that iron-
based additives, such as ferrocene and iron naphthenate,
can reduce carbon emissions.

Flame-Type Additives

Fuel atomizers are one category of flame-type additives.
Both Parsons (23) and Walker (29) reported that fuel-
atomizing additives containing ferrous picrate reduced
smoke from diesel engines. The commercial product
chosen for evaluation by the Bureau was FE-6 fuel
additive, which is available from Ferrous Corporation,
P.O. Box 1764, Bellevue, WA, 98009. (There are at least
two other sources for fuel additives containing ferrous
Picrate: Fuel Technology Pty Ltd., P.O. Box 100, Darra,
Queensland 4076, Australia, and FPC Enterprises, P.O.
Box 156, Evans City, PA, 16033.)

Combustion Catalysts

A ferrocene-based fuel additive was selected for eval-
uation because of claims that it enhanced combustion
through the formation of a catalytic ferric oxide (Fe,O, or
hematite) coating on the engine’s combustion surfaces.
This additive, Diesel Maxi-miser, is available commercially
from Econalytic Systems, Inc., 4845 Pearl East Circle,
Suite 300, Boulder, CO, 80301-2474.

The catalytic properties of ferric oxide are well known.
For example, one commercial method for producing
sulfuric acid used catalytic ferric oxide to oxidize SO, to
SO,, although platinum is probably the preferred catalytic
agent now (8). Miyamoto proposed that some metal-
based additives may inhibit soot formation at the beginning
of combustion and concluded that many metals including
iron"... have dramatic catalytic effects not only to
improve reaction rate but also to reduce activation energy
in soot oxidation..." (18-19).

Murray (21) measured gaseous emissions reductions for
an engine coated with an oxidation catalyst. Sapienza (24)
and Gaffney (9) plated the combustion surfaces of a diesel
engine with platinum. This procedure produced an initial
DPM reduction of 40 pet, but after 8 h of continuous
operation the DPM emissions were identical with those
measured before the application of the platinum, The
authors believed that the platinum was lost because of
poor adhesion to the walls, which were not prepared and
had surface impurities, including carbon.

‘Reference to specific products does not imply endorsement by the
U.S. Bureau of Mines.


16

CONCLUSIONS

Laboratory tests of two iron-based fuel additives were
conducted to evaluate their potential for reducing DPM
from engines of the type used in mines and to identify
adverse effects. One additive, ferrous picrate, did not
affect engine exhaust properties and specifically did not
measurably affect DPM.

The ferrocene-treated fuel produced red deposits in
the engine’s main combustion chamber. It is concluded
that the red coating is ferric oxide and that it acts as an
oxidation catalyst. The concentrations of all measured
exhaust emissions—CO, CO,, O,, GPHC, NO,, and DPM—
were affected by conditioning the engine with ferrocene-
treated fuel.

DPM concentrations were reduced for all tested engine
conditions compared with DPM concentrations before

the addition of ferrocene to the fuel. The DPM reduc-
tions ranged between 4 and 45 pct for six steady-state
engine operating conditions. The DPM reduction for an
8-min transient cycle was 37 pet.

At low and moderate fuel-air ratios, measurements
show that DPM changes were mainly the result of reduced
levels of VDPM. At high load conditions, however, an
analysis of the results showed that carbon levels must have
been substantially reduced also.

The major adverse effect of the ferrocene additive was
increased NO, levels at all tested conditions. The 12-pct
NO, increase, observed for the RDC, represents increases
that ferrocene-treated fuel might cause in actual mining
conditions.

REFERENCES

1. Ambs, J. Thermophoretic Deposition of Particles Inside the
Combustion Chamber of a Diesel Engine. M.S. Thesis, Univ. MN,
Minneapolis, MN, 1989, 98 pp.

2. Baranescu, R, A. Influence of Fuel Sulfur on Diesel Particulate
Emissions. (Pres. at Future Transp. Tech. Conf. and Exp., San Fran-
cisco, CA, Aug. 8-11, 1988). SAE 881174, 1988, 11 pp.

3. Baumgard, K, J., and K. L. Bickel. Development and Effective
ness of Ceramic Diesel Particle Filters. Paper in Diesels in Under-
ground Mines. BuMines IC 9141, 1987, pp. 94-102.

4. Bonczyk, P. A. Investigation of Fuel Additive Effects on Sooting
Flames (Final report, contract F49620-83-C-0113). Air Force Office of
Scientific Research 86-0851, 1986, 128 pp; NTIS AD-A172 522.

5. Cooper, B. J., and J. E. Thoss. Role of NO in Diesel Particulate
Emissions Control. SAE 890404, 1989, pp. 171-183; reprinted from
SP-775, Developments in Diesel Particulate Control Systems.

6. Cuthbertson, R. D., P. R. Shore, L. Sundstrom, and P. O. Heden,
Direct Analysis of Diesel Particulate-Bound Hydrocarbons by Gas
‘Chromatography with Solid Sample Injection. SAE 870626, 1987, 12 pp.

7. Draper, W. M., J. Phillips, and H. W. Zeller. Impact of a Barium
Fuel Additive on the Mutagenicity and Polycyclic Aromatic Hydrocar-
bon Content of Diesel Exhaust Particulate Emissions. SAE 881651,
1988, 19 pp.

8. Ehret, W. F. Smith's College Chemistry. D. Appleton-Century,
6th ed., 1946, pp. 351-352.

9. Gaffney, J., R. Sapienza, T. Butcher, C. Krishna, W. Marlow, and
T. O'Hare. Soot Reduction in Diese! Engines: A Chemical Approach.
Combust. Sci. and Technol, v. 24, 1980, pp. 89-92.

10. Golothan, D. W. Diesel Engine Exhaust Smoke: The Influence
of Fuel Properties and the Effects of Using Barium-Containing Fuel
Additive (Proc, Automotive Eng. Congr., Detroit, MI, Jan. 9-13, 1967).
SAE 670092, 1967, 23 pp.

11. Halsall, R,, and M. L. McMillan. An Improved Method for De-
termining the Hydrocarbon Fraction of Diesel Particulates by Vacuum
‘Oven Sublimation. (Pres. at Int. Fuels and Lubr. Meet. and Exp.,
Toronto, Ontario, Nov. 2-5, 1987). SAE 872136, 1987, 16 pp.

12. Kamimoto, T., and M. Yagita. Particulate Formation and Flame
Structure in Diesel Engines. (Pres. at Int. Congr. and Exp., Detroit, MI,
Feb. 27-Mar. 3, 1989). SAE 890436, 1989, 9 pp.

13, Kanne, D. D., and R. Y. Iwamoto. A Novel Approach to the Con-
trol of Heavy-Duty Diesel Particulate Emissions. SAE 880634, 1988,
28 pp.

14, Klarman, A. F. Evaluation of the Extended Use of Ferrocene for
Test Cell Smoke Abatement; Engine and Environmental Test Results.
Interim rep, NAVAIR AIRTASK NO. 5365360-0522-66231000. 1977,
123 pp; NTIS AD-A047 659.

15, Korsakova, I. S., S. V. Akimov, E. A. Nikitina, and A. I. Malkova,
Laboratory Method for Investigation of Smoke Suppressant Additives
for Middle Distillate Fuels. Chem. and Technol. Fuels and Oils, v. 17,
No. 7-8, Mar. 1982, pp. 426-428.

16. Kracklauer, J.J. Conditioning Diesel Engines. U.S. Pat. 4,389,220,
June 21, 1983.

17. Maiko, L. P., E. P. Seregin, M. O. Lemer, L. A. Aleksandrova,
V.I. Petrov, and V. T. Bugai. Improvement of Fuel Combustion
Process in Gas Turbine Engines by the Use of Additives. Chem. and
Technol. Fuels and Oils (Engl. Transl.), v. 13, No. 3-4, Mar.-Apr. 197,
pp. 253-256.

18. Miyamoto, N., Z. Hou, and H. Ogawa. Catalytic Effects of Metal-
lic Fuel Additives on Oxidation Characteristics of Trapped Diesel Soot.
SAE 881224, 1988, 7 pp.

19. Miyamoto, N., Z. Hou, H. Ogawa, and T. Murayama. Character-
istics of Diesel Soot Suppressions With Soluble Fuel Additives. SAE
871612, 1987, 7 pp.

20, Mogan, J. P., and E. D. Dainty. Emission Control Performance
of Diesel Exhaust Treatment Devices. Paper in Heavy-Duty Diesel
Emission Control: A Review of Technology, ed. by E. W. Mitchell.
Can. Inst. of Min. and Metall., Montreal, Quebec, CIM Spec. v. 36, 1986,
pp. 135-142.

21. Murray, R. G. Performance and Emission Characteristics of a
Semi-Adiabatic Engine. ASME Tech. Pap. No. 80-DGP-44, 1980, 12 pp.

22, National Institute for Occupational Safety and Health (Dep.
Health and Human Services). Carcinogenic Effects of Exposure to
Diesel Exhaust. Current Intelligence Bull. 50, DHHS (NIOSH) Publ.
No, 88-116, Aug. 1988.

23. Parsons, J.B, and G. J. Germane. The Effects of an Iron-Based
Fuel Catalyst Upon Diesel Fleet Operation. SAE SP-548, Aug. 1983,
pp. 51-61.



APPENDIX D.—ENGINE AND EMISSIONS DATA

Table D-1.—General test data

Test Fuel Engine Barometric
Date series Lot! Additive? condition —_ pressure,
time, h mm Hg

11/7/88 .. MASOOT 1 U 0 28.87
11/8/88 . masoo2 1 u 0 29.13
11/9/88 .. MAS101 1 M ) 28.97
11/17/88 MAS102 1 M 46 29.12
11/28/88 MAS103 2 M 101 29.11
12/9/88 . MASI04 2 M 178 29.40
12/22/88 MAS105 2 M 244 28.98

M_ Maintenance.

U__ Untreated.

1A fuel change occurred between conditioning times of 46 and 101 h.
2Maintenance concentration is 1,280 parts fuel to 1 part additive; condi-
tioning concentration is 320 parts fuel to 1 part additive.


CONTENTS

Abstract
Introduction
Problem
Fuel additives .. .
Background .
Flame-type additives .
Combustion catalysts
Objectives .....
Acknowledgments . .
Apparatus and procedures
Engine ....... tee
Particulate measurement
Gas emissions measurement
Experimental approach .....
Test plan for ferrous picrate
Test plan for ferrocene .
Baseline tests .....
Engine conditioning .
Data analysis . .
Experimental results for ferrous picrate
Experimental results for ferrocene .
Effects of ferrocene in engine’s combustion chamber .
Conditioning effects on exhaust properties .
Research duty cycle
Steady-state engine modes ..
Discussion and interpretation of experimental results :
Proposed mechanisms involving catalytic oxidation surfaces .
Effect of sulfates on particulate
Research recommendations
Conclusions
References .
Appendix A—Fuel comparison ......... 0.0... 0s see see eee
Appendix B.—Maintenance concentration effects on emissions . .
Appendix C.—Data analysis ..........00cce0eeeees bees
Appendix D.—Engine and emissions data............... .

ILLUSTRATIONS

1, Diesel engine testing facility .

2. Air intake and dilution systems .

3. Effect of ferrous picrate on DPM emissions at two concentrations of additi ‘ive in fuel .
4. Effect of ferrous picrate on CO emissions at two concentrations of additive in fuel .
5. Effect of ferrocene conditioning on exhaust parameters for multimode duty cycle . .
6.
7.
8.
9.

. Effect of ferrocene conditioning on CO emissions .
. Effect of ferrocene conditioning on NO, emissions .
, Effect of ferrocene conditioning on CO, emissions .
. Effect of ferrocene conditioning on O, emissions ....
10. Effect of ferrocene conditioning on DPM percentage .... .
11. Effect of ferrocene conditioning on DPM concentration . . .
12. Effect of ferrocene conditioning on solid DPM emissions . . . .
13. Effect of ferrocene conditioning on volatile DPM emissions . .

Page

BBB Beary wraaannnnVVUwNWNNNNNNE

Beane

21


100 . ,
E
5
Ey
ui
8
2
z
S100}
g KEY
rook Engine test modes |
Fa 24
z v2
° 6
8 -so0L.
8 -s00 ra
° = 10
° 14
-400 1 .
8 100 150

CONDITIONING TIME, h

Figure 6.—Effect of ferrocene conditioning on CO emissions.

8

T T T T

KEY

Engine test modes

NOx CONCENTRATION CHANGE, ppm

50 100 150
CONDITIONING TIME, h

—Effect of ferrocene conditioning on NO, emissions.

5

: T T T
KEY

Engine test modes

CO, CONCENTRATION CHANGE, ppm

250

CONDITIONING TIME, h

Figure 8.—Effect of ferrocene conditioning on CO, emissions.

2 Ae
Wi
8
2g
&
& KEY
£ Engine test modes‘,
2
gn 4
z v2
° 6
S20 a8
° = 10
° 34 aa
8g 700 150 200

CONDITIONING TIME, h

Figure 9.—Effect of ferrocene conditioning on O, emissions,


8

il

KEY
Engine test modes

&
N

8

x
8

3

2

RATIO OF EXTINCTION COEFFICIENT TO DPM

50 100 150
CONDITIONING TIME, h

Figure 14.—Effect of conditioning time on ratio of extinction
coefficient to DPM mass.

120 7 T T
° KEY
Conditioning time, h
§ 2 2 0
& 100; v 46 7
3 © 101
e 4178
é ° 28d
% 80 4
g
3
g So
£ eor |
&
40) s 4
0.01 0.02 0.03 O04 0.05

FUEL-AIR RATIO

Figure 15.—Effect of ferrocene conditioning on gas-phase
hydrocarbons (GPHC) emissions for steady-state loads at
2,300 r/min,

combustion product, CO levels can increase because of
improved fuel combustion, but also can decrease because
of complete combustion to CO,.

The increased NO, levels for all engine modes after
244 ha (fig. 7) confirm the hypothesis that ferrocene-treated
fuel enhances catalytic oxidation. After only 46 hvof con-
ditioning, NO, levels increased for modes 6, 8, 10, and 14,
consistent with the increase determined for the RDC at
46h (fig. 5), The variability at mode 1 and, to some
extent, for mode 2 is attributable to both instrument error
and the influence of prior engine operating conditions, as
discussed previously for GPHC variability at those modes.

T T T T
KEY
Conditioning time, h

130,

2 0

120 v 46 1
2 101

110F- 2 178 4
© 244

sok

GPHC CONCENTRATION. ppm
8

1. 1
0.02 (0.03
FUEL-AIR RATIO.

16.—Effect of ferrocene conditioning on gas-phase
hydrocarbons (GPHC) emissions for steady-state loads at
1,600 r/min.

0.06

CO, levels (fig. 8) increased with engine-conditioning
time, consistent with the enhanced oxidation hypothesis.
The maximum increase was more than 4,000 ppm for
mode 8, The increases for the remaining modes ranged
between 800 and 2,200 ppm.

Expressed as percent changes, the largest increase after
244 h was 8 pet for mode 2. The increases for modes 1,
8, and 10 were between 4 and 5 pct and were equivalent
to the 5-pct increase measured for the RDC. The CO,
concentration for mode 14 was about 120,000 ppm, so the
changes observed for this mode were less than 2 pet.
Because of this small percentage change, even small errors
in the measurement of fuel rate, airflow, and CO, con-
centration can account for the mode-14 variability ob-
served during the conditioning process.

The percent changes in O, levels for the steady-state
modes are shown in figure 9. The O, levels for all modes
continuously decreased after 46h to minimum values
(maximum change) at 178 h and then either increased or
remained approximately level at 244h, These data are
consistent with the O, trend for the RDC, for which the
percent changes are roughly equivalent to those of mode
10 and also showed a maximum change at 178 h.

The actual O, differences, expressed in parts per
million, during the conditioning process are summarized in
table 4. The results for the RDC are included for com-
parison. After 101 h all the values were negative, indi-
cating that more O, is consumed because of the condition-
ing process. The largest changes measured were 11,000
and 12,000 ppm extra O, consumption for mode 10 and
the RDC at 178 h.


Library of Congress Cataloging in Publication Data:

Zeller, H. William.
Effectiveness of iron-based fuel additives for diesel soot control / by H. William
Zeller and T.E. Westphal.
P. cm, — (Report of investigations; 9438)
Includes bibliographical references (p. 16).
1, Mine dusts. 2, Diesel fuels—Additives—Testing. 3. Ferrocene. I. Westphal,

T. E. (Terry E.). I. Title. Ill. Series: Report of investigations (United States.
Bureau of Mines); 9438.

TN23.U43  [TN312] 622 s—dc20 [622.83] 92-13640 CIP



20

APPENDIX B.—MAINTENANCE CONCENTRATION EFFECTS ON EMISSIONS

Two sets of baseline tests were conducted for all 15 test
conditions (modified SAE J1003 and the RDC) using
untreated fuel; these tests are designated as MAS001 and
MAS002 in appendix D. The baseline tests were imme-
diately followed by one set of tests, designated as MAS101,
with the ferrocene-based additive at the maintenance con-
centration of 1 part additive to 1,280 parts fuel.

The percent change (fig. B-1) for exhaust properties is
based on differences between the maintenance concentra-
tion values and the average of the two baseline measure-
ments. Ten exhaust properties are plotted in figure B-1.
Eight of the parameters for the maintenance concentration
set differed by less than 2 pct from those for untreated
fuel. Two of the parameters, extinction and GPHC, dif-
fered by more than about 5 pet from the untreated-fuel
levels.

Many of the small changes in figure B-1 are opposite to
the trends observed during the conditioning process and
suggest that the differences are due mostly to data scatter.
For example, O,, GPHC, and DPM levels increase in
figure B-1 while they decreased (for full-speed conditions
only for GPHC) during the conditioning process. CO,
and NO, levels decrease here but both increased through-
out conditioning. CO levels were inconclusive during
conditioning.

The extinction data plotted in figure B-2 show that
most of the variability (fig. B-1) is attributable to fuel-air
ratio effects at the mode-14 values over 0.05. The main
reason for the decrease of 9 pet is that the maintenance-
concentration test was conducted at a reduced fuel-air
ratio for mode 14 compared with the untreated-fuel ratios.

Extinction |
Temperature
02

CO.

co

PARAMETER

NO,
GPHC
OPM

Fuel-air ratio

10 5 0 S 10
CHANGE FROM UNTREATED FUEL, pct

Figure B-1.—Effect of maintenance concentration of ferrocene
on exhaust parameters. (GPHC = gas-phase hydrocarbons).

Note that the maintenance and untreated values agree well
for all fuel-air ratios less than 0.05.

The plot of GPHC data (fig. B-3) shows that the
increase of about 5 pct noted in figure B-1 is within the
range of data scatter observed.

Because 8 out of 10 exhaust parameters exhibit almost
no effects attributable to maintenance levels of additive
and because the extinction changes observed are attrib-
utable to fuel-air ratio variations, it is concluded that the
additive at the maintenance level had no measurable effect
on engine performance and on emissions.

10F T T 3
>, OF q
. q
o 2
Fa
Gib 4
S
E os
8 KEY
8 os 3
Zz Fuel treatment, test_ number
Bote ¥ Untreated,oo1 4
2 4 Untreated, 002
E 0.05 2 Treated, 101
inf

0.02

0.01 m .

o 0.02 0.04 0.06

FUEL-AIR RATIO

Figure B-2.—Effect of maintenance concentration of ferrocene
‘on extinction coefficients.

120, ;

T KE
. Fuel treatment, test number
Y Untreated. 001
vg 4 Untreated, 002
sooh * 2 Treated, 101 1
€
&
80h 1
2
a
&
$ %
eo g . |
4° O02 ory G06

FUEL-AIR RATIO

Figure B-3.—Effect of maintenance concentration of ferrocene
on gas-phase hydrocarbons (GPHC).


Report of Investigations 9438

Effectiveness of Iron-Based Fuel Additives
for Diesel Soot Control

By H. William Zeller and T. E. Westphal

UNITED STATES DEPARTMENT OF THE INTERIOR
Manuel Lujan, Jr., Secretary

BUREAU OF MINES
T S Ary, Director


Table D-2.—Engine load, sample time, and Intake conditions

Mode! Torque, Speed, Tim Intake press Mode? Torque, Speed, Time, _ Intake press
ftlb t/min ratio ftlb r/min min ratio
MAS102 (cont):
8 7330145 0.97 9... 135 2204 = NA 0.94
8 1594145 96 90 2204 145 94
52 1,595 145 96 45 2,294 = NA 34
105 1595 13.5 96 10 2,293 = NA 94
157 1,595 145 96 8 7320 ONA 98
212 1595 3.5 96 199 1,595 2 87
8 733 14.5 7 107 1522 8B 96
183 2207 5 94
138 2203 14.5 94 7 7320 14.5 a7
92 2294 © 12 94 7 1,594 14.5 95
46 2294 12 94 52 1,595 NA 95
10 2293 14.5 94 105 1,595 NA 96
8 732148 98 157 1,595 NA 96
201 1595 2 87 212 1596 «6 96
109 1526 8 96 8 731 NA 97
180 2297 8 93
8 731 14.5 98 135 2,294 NA 94
8 1,594 14.5 96 90 2295 145 94
52 1,595 14.5 95 45 2,293 «NA 94
105 1,595 13.5 95 10 2,293 0 «NA 94
157 1595 14.5 95 7 732 NA 98
210 15944 96 195 15962 86
7 7320145 97 106 1,527 8 94
180 22070 7 94
135 2204 145 94 7 732145 6
90 2,294 12 94 7 1994 14.5 6
45 2204 14.5 94 52 1,595 NA 96
10 2293 145 94 405 1,594 NA 96
8 732145 98 157 1,595 NA 96
198 1596 2 87 213 1,594 3 96
107 1525 8 96 8 731 NA 1.00
185 2298 «8 94
7 7310 145 7 135 2,295 NA 94
7 1594145 96 90 2204 145 94
52 1,595 145 96 45 2204 NA 94
105 1595 14.5 96 10 2,293 NA 94
157 1595 14.5 96 8 7320 ONA 7
207 159545 96 197 15952 87
8 7320 (14.5 97 108 1520 8B 96
17 2297 7 95
135 2204 145 94 7 731 145 a7
90 2293 145 94 7 1,596 14.5 96
45 2294 © 125 94 52 1,595 NA 95
10 2203 145 94 105 1,595 NA 6
8 732 145 7 157 1,595 NA 95
193 1596 2 86 212 1595 3 96
107 1,527, 8 96 8 731 NA 97
182 2297 8B 94
1 8 732145 98 135 2,294 NA 94
2 8 1594 14.5 96 90 2,294 14.5 94
3 52 1,595 NA 96 45 2,294 = NA 94
4 105 1,595 NA 6 9 2,293 «-NA 94
5 157 1,595 NA 96 7 731 NA a7
6 2n1 1596 9 96 194 1,594 2 87
7 8 733 NA 98 106 152408 96
8 181 2207, 8 95

NA Not available.

RDC Research duty cycle.

\Data sets MASOO1 and MASO02 are for fuel without ferrocene; MAS101, MAS102, MAS103, MAS104, and MAS105 are for fuel with the
maintenance concentration of ferrocene.


1,000, - : 1.200 : r r T
Rey 3 Key
sook Ferrous picrate Ferrous picrate
E concentration, wt pot ho J 1,000} concentration, wt pet 4
9 0.03 q ¥ 0.93
ool 80.88 J 2 033
‘00 — Untreated aool = —Untreated v J

sil

DPM CONCENTRATION, mg/m?

CO CONCENTRATION. ppm

0.03 0.04 0.05 0.06

FUEL-AIR RATIO.

101 n
0.0t 0.02

Figure 3.—Effect of ferrous plcrate on DPM emissions at two
concentrations of additive in fuel.

deposits (29). Claims of hydrocarbon and CO reduction
are probably based on data obtained after substantial
periods of engine operation with treated fuel and could
be the result of reduced engine deposits. The results ob-
tained in this study do not confirm or contradict claims

or 002-003 —~«O4—CSSSCSC~CHSSCO
FUEL-AIR RATIO.

Figure 4,—Effect of ferrous picrate on CO emissions at two
concentrations of additive In fuel,

for reducing engine deposits. The engine was not run long
enough to verify that property of the additive.

Based on these results, it is concluded that any changes
in fuel atomization caused by ferrous picrate have no
effect on particulate and gaseous emissions from a well-
maintained engine in good operating condition.

EXPERIMENTAL RESULTS FOR FERROCENE

EFFECTS OF FERROCENE IN ENGINE’S.
COMBUSTION CHAMBER

Before beginning the engine conditioning process with
ferrocene, one cylinder was disassembled and inspected for
carbon and residual deposits from previous tests of a
barium-based fuel additive. The combustion chamber sur-
faces were coated with a thin carbon layer that appeared
hard and durable. No evidence of barium compounds,
such as those described by Golothan (10), was observed.

Periodic examination of the glow plugs throughout the
conditioning phase revealed a steady accumulation of ared
deposit. Based on the experience of others, mainly the
chemical analysis by Klarman (14), the red deposits were
assumed to be ferric oxide.

It was anticipated that ferric oxide coatings were also
forming in the engine’s prechamber. When the condition-
ing phase was terminated, however, neither carbon nor
other coatings were observed on the prechamber surfaces,
which appeared smooth, reflective, and metallic. Only a
fraction of the prechamber could be examined, however,
because the only borescope available was too large to be
inserted through either the fuel injector or glow plug
openings. Consequently, the condition of most of the pre-
chamber surface is not known.

In the main combustion chamber, portions of the sur-
face were covered with the red oxide coating that had
displaced the carbon found in the initial inspection. The
ferric oxide deposits on both the piston crown and the
cylinder head were heaviest near the prechamber passage.

It was anticipated at the time of this inspection that
conditioning and testing would be resumed, so disturbance
of the coatings was restricted to minimal scratching of the
ferric oxide. Much of the oxide coating on the metal was
sufficiently hardened to resist the attempts to remove it
by scraping.

CONDITIONING EFFECTS ON EXHAUST
PROPERTIES

Research Duty Cycle

Engine conditioning effects on exhaust properties are
illustrated in figure 5 for the RDC. Three measurements
of each plotted parameter were obtained before beginning
the conditioning process. The averages of these three runs
are the engine baseline levels from which the percent
changes were calculated. The CO measurements after
101h are not available because of instrumentation
problems.


10

40 1

Oo
KEY

DPM CONCENTRATION CHANGE, pct

8

~150

DPM CHANGE, mg/m?

-20b _—
Engine test modes TM~s.,_
o 4
v2 -200
-40F 8 4
-250
= 10
60 ° 14 :
~ n fi L ~ 1 . L
) 50 100 150 200 250 300, 700 760 200

CONDITIONING TIME, h

Figure 10.—Effect of ferrocene conditioning on DPM per-

centagi

80 T

6oL

KEY
Engine test modes

re 11.—Effect
centration,

CONDITIONING TIME, h

of ferrocene conditioning on DPM con-

50, T

VDPM CONCENTRATION CHANGE, pct

KEY

SDPM CONCENTRATION CHANGE. pct

CONDITIONING TIME, h

Figure 12.—Effect of ferrocene conditioning on solid DPM

(SDPM) emissions.

~50r Engine test modes \,
o4
v2
o8
#10
-40 . 1 A : -100 . f A A
oO 50 100 150 200 250 fo 50 100 150 200

Figure 13.—Effect
(VDPM) emissions.

CONDITIONING TIME, h

of ferrocene conditioning on volatile DPM