Green Fuels and their impact on the performance and the exhaust gases in Diesel Engines

1. Green Fuels and their impact on the performance and the exhaust gases in Diesel Engines J. TRIANDAFYLLIS Professor in the Department of Vehicle Technology jtriand@vt.teithe.gr TEI OF THESSALONIKI

2. Contents • Introduction. • Effects on engine performance (these notes are based on bibliography source 3). • Measurements of two cars with diesel engines at the Karel de Grote- Hogeschool. • Bibliography. TEI OF THESSALONIKI

3. 1. Introduction THE SIGNIFICANCE OF PLANT OILS AS BIO-FUELS. • Bio-fuels are oils derived from plants, such as sunflower oil, cottonseed oil, and safflower oil. • Bio-fuels can be utilized in mixtures with diesel oil to improve the quality of the vehicle exhaust gases, and thus, to improve the air quality. • The air quality can be improved because the bio-fuels when are burnt, do not produce PAH (polyaromatic hydrocarbons), unburnt hydrocarbons, and products of sulphur. TEI OF THESSALONIKI

4. 2. Effects on Engine Performance 2.1 Heating Value • Since a bio-fuel is mixed with diesel, from now on, let us refer to it as biodiesel. • The most important property of a fuel is its lower heating value (LHV), because it affects the quality of combustion, and thus, the production of power. • The lower heating value of all biodiesels is lower than that of diesel. TEI OF THESSALONIKI

5. Production of Biodiesel TEI OF THESSALONIKI

6. 2. Effects on Engine Performance 2.2 Fuel economy • Fuel consumption can be calculated from the carbon dioxide emissions and an analysis of the fuel carbon content. • It is more accurate to combine CO2 emission measurements with a gravimetric measurement of fuel consumption. • From tests it was found that biodiesel and mixtures of biodiesel with diesel exhibit a fuel economy proportional to their lower heating value. TEI OF THESSALONIKI

7. 2. Effects on Engine Performance TEI OF THESSALONIKI

8. 2. Effects on Engine Performance 2.3 Torque and Acceleration • The torque is related to the energy level of the fuel. • Studies have shown torque reductions for biodiesel and biodiesel mixtures. • Acceleration is also reduced for biodiesel and biodiesel mixtures. • Therefore, horsepower is also reduced. TEI OF THESSALONIKI

9. 2. Effects on Engine Performance • Peak torque is not significantly affected up to 35% biodiesel. TEI OF THESSALONIKI

10. 2. Effects on Engine Performance 2.4.1 Durability studies • Engines run with biodiesel mixtures experience problems caused by • The appearance of coke deposits on the valves caused by low volatility fuel at light loads. • Plugged filters and injectors by unreacted mono-, di-, and triglycerides, free fatty acids, methanol and glycerol found in raw plant oils. • Pump failure caused by deteriorating seals. TEI OF THESSALONIKI

11. 2. Effects on Engine Performance 2.4.2 Elastomer compatibility • Many of the problems encountered in the durability studies are traced to the incompatibility of biodiesels with certain elastomers. • Methylesters cause the swelling of trilobutyldilene and nitrile rubber, a material that is commonly used in automotive seals and gaskets. • Fluorine containing elastomers do not swell at the presence of biodiesels. TEI OF THESSALONIKI

12. 2. Effects on Engine Performance 2.4.3 Biodiesel lubricity • Fuel lubricity is important because in many fuel pumps the moving parts are actually lubricated by the diesel fuel itself. • From tests it was shown that soybean and rapeseed oil methylesters have superior lubricity when compared to low sulfur diesels. TEI OF THESSALONIKI

13. 2. Effects on Engine Performance 2.5 Emissions • Diesel engines are regulated for smoke opacity, total nitrogen oxides (NOx), total particulate matter less than 10 μm (PM-10 or PM), carbon monoxide (CO), and total hydrocarbon (THC). • The useful diesel engine life is 290.000 miles. The diesel engines must meet the emissions criteria throughout their useful life. • Aldehydes and poly-aromatic hydrocarbons (PAH) are not currently regulated. They may be regulated in the future in order to minimize the amount of toxins in the air. • The quantity of CO and THC derived from diesel engines is generally small. For this reason biodiesel fuels are considered for their impact upon PM and NOx . TEI OF THESSALONIKI

14. 2. Effects on Engine Performance 2.5.1 Emissions in two-stroke engines • For two-stroke engines without timing changes or exhaust catalyst, the use of biodiesels cause the following changes in the emissions • NOx increases • PM, CO and THC decrease • The soot (solid carbon fraction of PM) decreases. TEI OF THESSALONIKI

15. 2. Effects on Engine Performance 2.5.1Emissions in two-stroke engines(cont.) As the Oxygen content in the Biodiesel mixture increases, the NOx increases and the PM decreases. TEI OF THESSALONIKI

16. 2. Effects on Engine Performance 2.5.1 Emissions in two-stroke engines (cont.) From dynamometer and chassis tests on two-stroke engines, it was found that • The PM emissions depend on engine wear because worn engines slip oil past the rings to the air intake ports. • The NOx emissions are independent of engine type, injector technology, and wear. TEI OF THESSALONIKI

17. 2. Effects on Engine Performance 2.5.1 Emissions in two-stroke engines (cont.) • Retarding the injection timing from 1-4o of older engines run with soy biodiesel, the emissions of NOx were decreased to the level of the engine run with only diesel. At the same time, the PM emissions increased since the NOx were decreased. • This can be theoretically corrected by the presence of an oxidation catalyst. In practice the catalyst does not “capture” the liquid oil droplets and soot and cannot oxidize them. • The general conclusion is that biodiesel increases NOx and decreases hydrocarbons and CO. PM emissions decrease or stay constant for worn engines. TEI OF THESSALONIKI

18. 2. Effects on Engine Performance 2.5.2 Emissions in four stroke-engines Tests showed a similar behavior on emissions between four- and two-stroke engines. TEI OF THESSALONIKI

19. 2. Effects on Engine Performance 2.5.2 Emissions in four stroke-engines (cont.) • However, the NOx emissions rise much slower with increasing oxygen content than in the two-stroke engines. This can be explained from the fact that modern four-stroke engines have sophisticated electronic controls that vary the fuel injection timing and other engine parameters to minimize emissions. • The PM emissions decrease more rapidly in four-stroke than in two-stroke engines. This can be attributed to the fact that four-stroke engines are more efficiently lubricated and thus, have lower liquid oil emissions, typically 30% lower than in the two-stroke. TEI OF THESSALONIKI

20. 2. Effects on Engine Performance 2.5.2 Emissions in four stroke-engines (cont.) • The use of an oxidation catalyst yields enhanced PM emissions reduction. The presence of such catalyst and the use of a biodiesel mixture can reduce the PM emissions by 50%. • One can reduce the NOx emissions by increasing the cetane number or decreasing the aromatics. • Retarding the injection timing produced similar results, except that the NOx emissions were smaller. At the same time the PM emissions increased. TEI OF THESSALONIKI

21. 2. Effects on Engine Performance 2.6 Smoke opacity • Tests showed that in two-stroke engines the use of biodiesels did not reduce smoke opacity. • However, the combination of an oxidation catalyst and biodiesel produced a significant reduction in smoke opacity, especially in the lugging mode (lugging: engine at low speed under high load). TEI OF THESSALONIKI

22. 2. Effects on Engine Performance 2.7 Air toxins • The use of biodiesels increases the emission of liquid oil droplets from the lube oil or from the fuel. • There is a decrease of PAH emissions and in the mutagenic activity of the diesel exhaust with the use of biodiesels. TEI OF THESSALONIKI

23. 3. Measurements at the Karel de Grote-Hogeschool and at TEI of Thessaloniki 3.1 Introduction Measurements were made by the staff of Professor M. Pecqueur on two cars in the Combustion Laboratory in the Department of Industrial Sciences and Technology of the Karel de Grote-Hogeschool, Hoboken, Belgium. Similar measurements were done by the staff of Professor John Triandafyllis in the Department of Vehicles at TEI of Thessaloniki on one car. The cars were run under full load at 30, 50, 90 and 120 km/h speeds. TEI OF THESSALONIKI

24. Bio-fuels used Two bio-fuels were chosen to be converted chemically to bio-diesels: • Cottonseed oil, which was produced in Macedonia, Greece. • Used cooking oils which were collected in the city of Antwerp, Belgium. The conversion to bio-diesels was accomplished by Professor Serge Tavernier in the Department of Industrial Sciences and Technology of the Karel de Grote-Hogeschool, Hoboken, Belgium. TEI OF THESSALONIKI

25. 3. Investigation goals • Performance of the diesel engines run with the bio-diesel mixtures as compared to their performance run only with diesel. • Two fuel temperatures were used, at 20oC and at 40oC in order to investigate the effect of the fuel temperature. • The engines were run at two different values of injection timing, -5o and +5o in order to investigate the effect of the injection timing upon NOx and soot in the exhaust gases. TEI OF THESSALONIKI

26. Investigation goals • TO COMPARE THE EMISSIONS OF PM, NOx AND CO2 BETWEEN DIRECT AND INDIRECT IGNITION ENGINES FUELED BY THE SAME METHYLESTER MIXTURES. TEI OF THESSALONIKI

27. TEST VEHICLES TEI OF THESSALONIKI

28. TEST CONDITIONS IN THE DYNAMOMETER TEI OF THESSALONIKI

29. TEST EQUIPMENT TEI OF THESSALONIKI

30. Performance VOLVO diesel engine TEI OF THESSALONIKI

31. Performance FORD diesel engine TEI OF THESSALONIKI

32. Effect of fuel temperature TEI OF THESSALONIKI

33. Effect of injection timing TEI OF THESSALONIKI

34. Effect of bio-diesel content TEI OF THESSALONIKI

35. Conclusions • The conversion of the pure cottonseed oil and of the used cooking oil into bio-diesel produced fuel that at 40oc exhibited excellent properties, especially in the value of their viscosity that approached that of diesel. With the mixtures of these two bio-diesels with diesel as fuel, both cars ran smoothly, even at 100% bio-diesel. • The chassis measurements at full load showed a 10% increase in engine power when run with the mixtures of bio-diesel. • The fuel temperature change did not affect the power measurements. There was a small increase in the soot and NOx values when the fuel temperature increased. TEI OF THESSALONIKI

36. Conclusions • With increasing bio-diesel content the soot values dramatically decrease as compared to pure diesel as a fuel; the soot value was measured at 601 mg/m3 with diesel as a fuel as compared to 174,45 mg/m3 with B100 cottonseed bio-diesel. • The injection timing was changed from its factory value by 5o , delaying it and advancing it. There was an increase in soot and a decrease in the NOx values with advanced timing as compared to delayed timing. TEI OF THESSALONIKI

37. TEST RESULTS TEI OF THESSALONIKI

38. TEST RESULTS TEI OF THESSALONIKI

39. TEST RESULTS TEI OF THESSALONIKI

40. CONCLUSIONS • PM emissions are consistently lower for all biodiesel blends as compared to neat diesel. This decrease is more pronounced at lower power levels. • NOX emissions are consistently higher for all biodiesel blends as compared to neat diesel. This increase is more pronounced at higher power levels. NOX emissions increase in the Volvo and Ford Transit, but they do not vary appreciably in the Ford Escort. • CO2 emissions with all blends are consistently lower in the VOLVO engine, increase in the FORD ESCORT and do not vary appreciably in the FORD TRANSIT engine when compared to neat diesel, except at the fourth gear. TEI OF THESSALONIKI

41. DIRECT vs. INDIRECT • With regards to lower NOX emissions in the Ford Escort it should be noted that the combustion temperature in an IDI engine is lower than in a DI engine due to higher heat losses in the area of the prechamber, and therefore NOX emissions are reduced. • Other reasons for explaining the data differences are the presence of an ECU management system in the VOLVO, the EGR system for the recirculation of the exhaust gases in the VOLVO and FORD TRANSIT engines and the absence of an ECU or EGR system in the Greek FORD ESCORT. TEI OF THESSALONIKI

42. Bibliography • Mariusz Ziejewski and Hans J. Goettler, Design Modifications for Durability Improvements of Diesel Engines Operating on Plant Oil Fuels. In SAE Paper 921630, 1992. • Higelin P., Huiles vegetales –biocombustible Diesel, Incidence des aspects thermiques lies au type de moteur sur la combustion’’.These de l’univercited’Orleans, 1992. • Michael S. Graboski and Robert L. McCormick, Combustion of Fat and Vegetable Oil Derived Fuels in Diesel engines. In Prog. Energy Combust., 1998, Vol. 24, 125. • J. Triandafyllis, Sp. Katopodis, F. Vosniakos, V. Grammatikis, E. Kalafatis, D. Mantzaris, and Ch. Mallas, The Use of Sunflower Oil in Direct Injection Engines. Accepted to be printed in Journal of Environmental Protection and Ecology. • Goyal M., Biodiesel research-Deere power-diesel engine durability issues using biodiesel. Presented at Commercialization of biodiesel: Establishment of Engine Warranties, University of Idaho National Center for Advanced Transportation Technology, 1994. TEI OF THESSALONIKI

43. Bibliography 6. Howell S., Lubricity of biodiesel fuel: Update No. 3. Report to National Biodiesel Board, MARC-IV, Kansas City, MO, 21 July 1994. 7. S.Kalligeros, F.Zannikos, S.Stournas, E.Lois, G.Anastopoulos, Ch.Teas, F.Sakellaropoulos, An investigation of using biodiesel performance of a stationary diesel engine/marine diesel blends on the performance of a stationary diesel engine. In Biomass & Bioenergy, 2003, 24, 141. 8. G.Amba Prasad Rao, P.Rama Mohan, Effect of supercharging on the performance of DI Diesel engine with cotton seed oil. In Energy Conversion and Management, 2003, 44, 937. 9. Barsic NJ, Humke AL, Vegetable oils: Diesel fuel supplement. In J. Automobile Eng, 1981, 89(4),37. • Mohamad I. Al-Widyan, Ghassan Tashtoush, Moh’d Abu-Qudais, Utilization of ethyl ester of waste vegetable oils as fuel in diesel engines. In Fuel Processing Technology, 2002, 76, 91. 11. P.N. Giannelos, F. Zannikos, S. Stournas, E. Lois , G. Anastopoulos, Tobacco seed oil as an alternative diesel fuel: physical and chemical properties. In Industrial Crops and Products, 2002, 16, 1. TEI OF THESSALONIKI

44. Bibliography 12. Abdul Monyem,Jon H.Van Gerpen, The effect of biodiesel oxidation on engine performance and emissions. In Biomass and Bioenergy, 2001, 20, 317. 13. Ghassan Tashtoush, Mohamad I.Al-Widyan, Ali O.Al-Shyoukh, Combustion performance and emissions of ethyl ester of a waste vegetable oil in a water-cooled furnace. In Applied Thermal Engineering, 2003, 23, 285. 14. Mariusz Ziejewski and Hans J. Goettler, Limited Durability of the Diesel Engine with a Dual-Fuel System on Neat Sunflower Oil. In SAE Paper 950055, 1995. 15. J.A.Lopez Sastre, J. San Jose Alonso, C.Romero-Avila Garcia, E.J.Lopez Romero-Avila, C.Rodriguez Alonso, A study of the decrease in fossil CO2 emissions of energy generation by using vegetable oils as combustible. In Building and Environment,2003, 38, 129. 16. Agarwal AK., Vegetable oils verses diesel fuel: development and use of biodiesel in a compression ignition engine. In TIDE 1998, 8(3), 191. 17.Sinha S., Misra NC., Diesel fuel alternative from vegetable oils. In Chem. Engng World, 1997, 32(10), 77. 18. Roger AK, Jaiduk JO, A rapid engine test to measure injector fouling in diesel engines using vegetable oil fuels. In J. Am. Oil Chem. Soc.,1985, 62(11), 1563. TEI OF THESSALONIKI