Investigations on the use of Jatropha oil and its methyl ester as a fuel in a compression ignition engine

Vegetable oils can be directly used in compression ignition engines. Howeve r, their performance is slightly inferior to diesel. This is due to their h igh viscosity and carbon residue. The performance of vegetable oils can be improved by esterifying them. In this experimental work, performance, emiss ions and combustion characteristics of a single-cylinder, water-cooled, dir ect-injection diesel engine running on Jatropha oil and its methyl ester we re evaluated and compared with diesel operation. With Jatropha oil, the max imum brake thermal efficiency was 25.6% compared with 29.4% with diesel. Th e thermal efficiency was 27.8% with the methyl ester of Jatropha oil. Smoke and particulate levels were higher with Jatropha oil than diesel. The meth yl ester of Jatropha oil was better than the pure oil but it was still infe rior to diesel. Hydrocarbon and carbon monoxide emissions were slightly hig her with both Jatropha oil and its methyl ester than with diesel whereas NO levels were lower than with diesel. Ignition delay and combustion duration were longer and peak heat release rates were lower with Jatropha oil and i ts methyl ester than with diesel. Again the methyl ester of Jatropha oil wa s better. On the whole it is concluded that the methyl ester of Jatropha oi l could be used unmodified in diesel engines with no major detoriation in p erformance. The long-term effects of this fuel have to be evaluated.