-s^-\.*^ •^ ^^ J. - .-N"^ ■>> • 1 ^ M' *5 '0^ _ .^' \^^^ f~- " ou 1 1 1 1 KEY ^Ov E ngine speed, r/min A □ 1,500 A 1,840 ^ V 2,060 A O 2,300 40 D D D D 20 - a - n 1 O A V 1 D D A D O A A V o V O A O a A n lA 0.01 0.02 0.05 0.03 0.04 FUEL-AIR RATIO Figure 10.-VDPM emissions from Deutz engine for untreated fuel. 0.06 10 E < cc LU o z o o CO C/5 < a. Q > 0.03 FUEL-AIR RATIO 0.05 Figure 11. -Additive effect on VDPM from Deutz engine at full speed. Comparison of Solid and Volatile Fractions The results (fig. 12) for full engine speed and the small intake restriction were selected to illustrate the relative levels of the solid and volatile particulate components for both treated and untreated fuels. For the Deutz engine and for both treated and untreated fuel, the solid fraction (SDPM) is the main component of DPM for fuel-air ratios greater than about 0.025, while at smaller fuel-air ratios the volatile fraction (VDPM) is the main constituent of DPM. The most obvious effect of the additive is reduction of the solid component, although, as noted in previous sections, some volatile reduction also occurs. Also (fig. 12), for treated fuel (0.09 wt pet), the nearly constant level of SDPM between 30 and 40 mg/m^, in conjunction with the results in figure 6, suggests a mini- mum DPM level and maximum effectiveness of DPM reduction using barium. At full load, the barium rate into the engine, for 0.09-wt-pct additive in the fuel, is 52 mg/min. If all the barium is emitted as barium sulfate (7) in the exhaust, the concentration is about 25 mg/m^, the major portion of the SDPM emitted. There are other unknown substances in this commercial additive that may also be emitted as solid components in the exhaust. The point is that the composition of the additive may be a significant limiting factor in DPM reduction; therefore, it is important to use only sufficient additive to achieve the required or desired effectiveness. 200 KEY Emission, treatment 150 DPM, untreated SDPM, untreated SPDM, 0.09 wt pet VDPM, untreated VDPM, 0.09 wt pet 100 0.03 FUEL-AIR RATIO 05 Figure 12.-Comparison of solid and volatile particulates from Deutz engine at full speed for small intake restriction. 11 HYDROCARBON EMISSIONS Gaseous Hydrocarbons The untreated-fuel GPHC mass concentration emissions are plotted (fig. 13) for all test conditions. The range of GPHC concentrations (plotted as methane equivalent) is large-between 10 and 80 mg/m^. There will be no at- tempt to identify trends, because of the complex inter- actions among engine speed, engine load, and engine in- take conditions. An additional complicating factor is the probability that a substantial fraction of the GPHC orig- inates from the engine lubricating oil, especially at light loads and high speeds (12). GPHC emissions for both treated and untreated fuels are plotted in figure 14, where the untreated-fuel data are the same as those plotted in figure 13. It is apparent that the main effect of the additive is to reduce the overall range of the GPHC emissions, especially at fuel-air ratios greater than 0.025. The minimum GPHC level observed for treated fuel is about 25 mg/m^, compared with the minimum of about 10 mg/m^ observed for untreated fuel. The increase in GPHC for treated fuel can be explained by referring back to figure 11, which showed that the con- densed volatiles, or VDPM, were decreased, on the aver- age, by barium-treated fuel. Consequently, it follows that if the exhaust hydrocarbons do not condense on the par- ticulate fraction, then they must remain in the gas phase as observed. What is not explained is why the GPHC levels for treated fuel (fig. 14) decrease with increasing additive concentration. Additive effects on exhaust hydrocarbons are examined further in the following section. ou 1 V 1 1 1 KEY V Engi ne speed, r/min A 1,500 ^ 60 aO V 1,840 O 2,060 - E D □ 2,300 2f O o A 1- < „o o a: 1- V O V 2 uj 40 O " A ° O V 7 — z v: s ($> V A A o D V o V g w O A A '^ i-i < A °A A A 2 D ^ 20 - D - Q. (5 O a o O 1 1 1 1 0.01 0.02 0.03 0.04 FUEL-AIR RATIO 0.05 0.06 Figure 13.-GPHC concentrations (plotted as methane equivalent) from Deutz engine for untreated fuel. 12 ou 1 1 A D 1 1 1 KEY D Additive, wt pet V D 0.00 n O A 0.09 t 60 _ CP V 0.18 _ E O 0.36 z ^ o D h- < □ ° ^ ^ 1- 1 40 V n ° _ z □ O^D A „ D V O o A CO CO < 5 D ^ 20 D D _ Ql o 1 1 1 1 1 0.01 0.02 0.03 FUEL-AIR RATIO 0.04 0.05 0.06 Figure 14.-GPHC concentrations (plottecJ as methane equivalent) for different additive concentrations and for all Deutz engine conditions. Total Exhaust Hydrocarbons Diesel exhaust is a complex, dynamic system in which the physical and chemical properties of the species present continuously change with time. For the purpose of this discussion, the following are assumed: (1) The diluted exhaust, from which the filter sample is extracted, is rep- resentative of the state of the VDPM in the exhaust pipe; that is, adsorption, desorption, and condensation are fully quenched at the instant of dilution; (2) the heated gas sampling line provides a representative GPHC sample to the instruments. If these conditions are met, then an estimate of TEHC is determined as follows: TEHC - VDPM + GPHC, when expressed in consistent units such as mass concentration. Calculated values of TEHC are plotted (fig. 15) against fuel-air ratio. No strong trends are apparent. Of more interest are the treated-fuel levels of TEHC for full-speed conditions (fig. 16) along with untreated-fuel data also for full-speed conditions; all three intake conditions are plot- ted here. There are two observations. First, the average TEHC levels do not appear to be substantially changed when all treated-fuel results are compared with all untreated-fuel data. Additive effects on TEHC are not significant relative to the reductions measured for SDPM (fig. 9). On the other hand, looking only at the treated- fuel results, TEHC levels appear to decrease with increas- ing additive concentration, as a result of the decrease in GPHC levels with increasing barium concentration. TOXIC GASEOUS EMISSIONS Nitrogen Oxides Nitrogen oxide emissions for different speeds, loads, intake restrictions, and additive treatments are plotted against fuel-air ratio (fig. 17). In general, nitrogen oxide formation increases with temperature and with the avail- ability of oxidizing agents during combustion. For exam- ple, combustion temperature is related directly to fuel-air ratio and in-cylinder oxygen concentration is related in- versely to fuel-air ratio. As a result, some of the nitrogen oxide emission plots (fig. 17) peak at about a fuel-air ratio of 0.04. For untreated fuel, the lowest nitrogen oxide levels of about 100 mg/m^ were measured for the largest restriction (minimum oxygen) and low fuel-air ratios corresponding to minimum temperatures. The highest levels for un- treated fuel, around 800 mg/m^ were for the smallest intake restriction (higher oxygen levels) and high fuel-air ratios (high temperatures). E < LU o z o o CO CO < o X LJJ 150 100 50- 0.01 xP o V . n 13 KEY Engine speed, r/min D 1,500 A 1,840 V 2,060 O 2,300 O V ^ ^ A O 07. O D O D A A D V D 0.02 0.03 0.04 FUEL-AIR RATIO 0.05 0.06 Figure 15.-TEHC concentrations for untreated fuel and all Deutz engine conditions. E 2f o I- < cc h- z UJ o z o o CO CO < o X LU 1 1 1 1 1 KEY Adciitive, wt pet ^D D 0.00 A 0.09 n^ V 0.18 % o 0.36 100 - - C^ A cn D V 50 > < 1 1 D 1 mA D o Aq D ° 1 1 0.01 0.02 0.03 0.04 FUEL -AIR RATIO 0.05 0.06 Figure 16.-TEHC concentrations from Deutz engine for treated fuel at full speed. 14 E 2 O I- < DC LU o z o o CO CO < ,uuu 1 1 1 1 O 1 KEY o Restriction. Additive. O o in HjO wt pet n ■ * 800 D 8 " D . D '-' '^ n n o A V«D A?^ _ A 28 • V 53. ■ 8' D ▲ 28 ■ 0.09 Oa % ^ D \l " ▼ 53. % ▼ 600 ~ O 8 0.36 & A ^ A - A ▼ V A A D A A OA 400 ■ A A A A A V V 200 1 A V 1 1 1 1 0.01 0.02 0.03 0.04 FUEL-AIR RATIO 0.05 0.06 Figure 17.-Comparison of nitrogen oxide concentrations from Deutz engine for treated and untreated fuels. Overall, the treated-fuel nitrogen oxide levels were greater than those measured for untreated fuel at the same fuel-air ratios. The 0.36-wt-pct additive treatment and small restriction produced the highest nitrogen oxide levels for a given fuel-air ratio. This general increase in nitrogen oxide levels for treated fuels is assumed to be the result of the oxidizing effect of barium. These results again empha- size the importance of not using any more additive in the fuel than necessary for DPM reduction. Carbon Monoxide The carbon monoxide exhaust emissions are plotted (fig. 18) against fuel-air ratio. The effect of the additive on carbon monoxide levels is mixed, which suggests that the additive will produce neither positive nor negative effects on carbon monoxide in the exhaust. ENGINE COMPARISON The purpose of this section is a limited comparison of the DPM emissions from two different engines: the Deutz engine tested in this research and a Caterpillar 3304 engine evaluated earlier (7-8). The comparison is limited because test data for the Caterpillar engine are available only for low-speed tests at 1,200 r/min or 67 pet of the full-rated speed (1,800 r/min) for that engine. The DPM emissions for untreated fuel (fig. 19) are expressed in power-specific mass rate to help account for the differences in the test loads and speeds for the two engines. Over the full range of fuel-air ratios, the Cat- erpillar engine emissions are smaller than those from the Deutz engine, including the full-speed Deutz engine data. DPM emissions are shown in figure 20 for a fuel treat- ment of 0.18 pet (the smallest concentration data avail- able for the Caterpillar engine) for both engines, plus 0.09- wt-pct additive results for the Deutz engine. The data show that for treated fuel the Deutz engine emits less DPM at most fuel-air ratios. In other words, the additive appears to be more effective for the Deutz engine, with the qualification that this result may be related to the fact that the speed of the Deutz engine was greater- 1,840 r/min (80 pet of full-rated speed) compared with 1,200 r/min for the Caterpillar engine (67 pet of full-rated speed). If the two engines could be compared at the same speeds, the results might be different. 15 500 400- E I 300 < tr. UJ o z o o o o 200- 100 1 KEY 1 1 1 1 Restriction, Additive. in HjO wt pet D 8 " A 28 0.00 ▼ A V 53 A 28 \ T 53 J 0.09 V A V ■ A^ 67 V A DA °A V - ■ 1 8^ D D D 1 1 1 1 - 0.01 0.02 0.03 0.04 FUEL-AIR RATIO 0.05 0.06 Figure 1 8.-Comparison of carbon monoxide concentrations from Deutz engine for treated and untreated fuels. 10 25 20 P 15 - Q 10 1 1 I Ia 1 KEY D Caterpillar 1 ^ A Deutz '. ^ f f ^ a\ a/ \a f 1 A / / A/ D - j ^ \ / / ^ / J / P A \ / / / \ \ A / ^ / a ~ \ \ 'A. / \ \ /a X \^ \^ A / jf A * t^ 1 1 — 5 f 0^ ° 1 1 0.01 0.02 0.03 0.04 FUEL-AIR RATIO 0.05 0.06 Figure 19.-Comparison of DPM from Deutz and Caterpillar engines for untreated fuel. 0.02 KEY □ Caterpillar A Deutz -^ r^i- ' _L. 0.03 0.04 FUEL-AIR RATIO 0.05 0.06 Figure 20.-Comparison of DPM from Deutz and Caterpillar engines for treated fuel. 16 CONCLUSIONS AND RECOMMENDATIONS At fuel-air ratios between 0.01 and 0.052, the DPM emissions of the Deutz engine ranged between 35 and 420 mg/m^. For fuel-air ratios up to about 0.04, the maximum DPM levels measured were less than about 120 mg/m^, a result that emphasizes the importance of operation at high speed with minimum intake restrictions (clean air filters) in order to maintain low fuel-air ratios. The DPM emissions from the Deutz engine were com- pared with those from a Caterpillar engine. For untreated-fuel operation, the DPM levels from the Cater- pillar engine were less than those from the Deutz engine over the entire range of fuel-air ratios tested. For maximum DPM reduction over the entire range of fuel- air ratios, the most effective additive concentration evaluated was 0.09 wt pet. Only at the maximum fuel-air ratios tested did the manufacturer's recommended concen- tration of 0.36 wt pet seem to impart a marginal additional benefit in reducing DPM compared with the 0.09-wt-pct treatment. Additive concentrations as low as 0.02 wt pet were observed to produce some DPM reductions. The effect of the additive on nitrogen oxide and carbon monoxide emissions was complex. Overall, nitrogen oxide levels tended to increase while carbon monoxide levels remained within the xmtreated-fuel range. Because emis- sion levels of both these gases are well within acceptable limits for the tested conditions and because the changes are small, the effect of the additive on nitrogen oxide should be considered in mine applications but is not ex- pected to be a problem for well-maintained engines and properly ventilated mines. This barium-based additive is recommended for re- ducing DPM emissions from diesel-powered equipment used in xmderground mines if the following conditions are met: 1. The additive reduces excessive particulate levels and is used mainly in equipment having heavy work-duty cycles involving substantial periods of full or near-full load operation. 2. The additive is used at the minimum concentration required to produce the measured DPM reduction ob- served. Based on results in this report, the suggested concentration is 0.09 wt pet. 3. Potential adverse effects such as unacceptable nitro- gen oxide increases should be checked. REFERENCES 1. National Institute for Occupational Safety and Health. Carcinogenic Effects of Exposure to Diesel Exhaust. U.S. Dep. Health and Hum. Serv., Public Health Serv., Curt. Intelligence Bull. 50, 1988, 30 pp. 2. Baumgard, K. J., and K. L. Bickel. Development and Effectiveness of Ceramic Diesel Particle Filters. Paper in Diesels in Underground Mines. Proceedings: Bureau of Mines Technology Transfer Seminar, Louisville, KY, April 21, 1987, and Denver, CO, April 23, 1987. BuMines IC 9141, 1987, pp. 94-102. 3. Waytulonis, R. W., and G. Dvorznak. New Control Technology for Diesel Engines Used in Underground Coal Mines. Paper 42 in Proceedings of the 3rd Mine Ventilation Symposium (Oct. 12-14, 1987, University Park, PA). Soc. Min. Eng. AIME, 1987, pp. 279-285. 4. Truex, T. J., W. R. Pierson, D. E. McKee, M. Shlef, and R. E. Baker. Effects of Barium Fuel Additive and Fuel Sulfur Level on Diesel Particulate Emissions. Environ. Sci. and Technol., v. 14, No. 9, 1980, pp. 1121-1124. 5. Kittleson, D. B., D. Dolan, R. B. Diver, and E. Aufderheide. Diesel Exhaust Particle Size Distributions-Fuel and Additive Effects. Sec. in The Measurement and Control of Diesel Particulate Emissions. SAE/PT-79/17, 1979, pp. 233-244. 6. Hare, C. T., and K. J. Springer. Fuel and Additive Effects on Diesel Particulate Development and Demonstration of Methodology (Pres. at Automot. Eng. Congr. and Expo., Detroit, MI, Feb. 23-27, 1976). SAE Tech. Paper 760130, 1976, 29 pp. 7. Zeller, H. W. Effects of Barium-Based Additive on Diesel Exhaust Particulate. BuMines RI 9090, 1987, 40 pp. 8. . Measurement of the Effects of a Fuel Additive on Diesel Soot Emissions. Paper in Diesels in Underground Mines. Proceedings: Bureau of Mines Technology Transfer Seminar, Louisville, KY, April 21, 1987, and Denver, CO, April 23, 1987. BuMines IC 9141, 1987, pp. 79-93. 9. Society of Automotive Engineers (Warrendale, PA). SAE Handbook: Engines, Fuels, Lubricants, Emissions, and Noise. V. 3, 1982, p. 24.10. 10. Sauerteig, J. E., and G. Perkuhn. Influence of Maintenance on the Exhaust Emission Quality of Diesel Engines. Paper in Diesel Use Seminar. Am. Min. Congr., 1988, pp. 118-144. 11. MWM Diesel, Inc. (Norcross, GA). MWM Mining Engines. Bull. 662, Feb. 1986, 10 pp. 12. Mayer, W. J., D. C. Lechman, and D. L. Hilden. The Contribution of Engine Oil to Diesel Exhaust Particulate Emissions. SAE Tech. Paper 800256, 1980, pp. 247-256. 17 APPENDIX.-ADDITIVE SPECIFICATIONS Supplier: Lubrizol Corp. 29400 Lakeland Blvd. Wickliffe, OH 44092 Type: Lubrizol 565 Recommended concentration: 0.36 wt pet or 0.25 vol pet (or 1,075 lb per 1,000 barrels of fuel) Physical and chemical properties: Specific gravity at 60° F 1.22 Viscosity at 100° C cSt . . 9.62 Barium content wt pet . . 20-25 Sulfur content wt pet . . 0.25-0.50 Nitrogen content wt pet . . 0.4-0.6 INT.BU.OF M1NES,PGH.,PA 29072 •0 m z S2. -* fl> • > 5 O ■n ■n -n O O - £ |! 3 73 > "0 r~ o- 2 «> 31 1 03 c m c 0) m z m JO- ^ §2 g" (/) ^ (/J _ 1 (j> 00 2. O O o -« > z m O c > r— O -D TJ O 3] H C Z m O -< m 33 396 90 • fy ,<°<. . %/ /.^*v \..<^^ .^i^^l£^^o %^j ^''^^-. . .* .«.♦ •% "• ^c,- .Ho^ .. •*-- fl5 °^ -1 ^^-n^. 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