A Comparison of the Different Methods of Using Jatropha Oil as Fuel in a Compression Ignition Engine

Different methods to improve the performance of a jatropha oil based compression ignition engine were tried and compared. A single cylinder water-cooled, direct injection diesel engine was used. Base data were generated with diesel and neat jatropha oil. Subsequently, jatropha oil was converted into its methyl ester by transesterification. Jatropha oil was also blended with methanol and orange oil in different proportions and tested. Further, the engine was modified to work in the dual fuel mode with methanol, orange oil, and hydrogen being used as the inducted fuels and the jatropha oil being used as the pilot fuel. Finally, experiments were conducted using additives containing oxygen, like dimethyl carbonate and diethyl ether. Neat jatropha oil resulted in slightly reduced thermal efficiency and higher emissions. Brake thermal efficiency was 27.3% with neat jatropha oil and 30.3% with diesel. Performance and emissions were considerably improved with the methyl ester of jatropha oil. Dual fuel operation with methanol, orange oil, and hydrogen induction and jatropha oil injection also showed higher brake thermal efficiency. Smoke was significantly reduced from 4.4 BSU with neat jatropha oil to 2.6 BSU with methanol induction. Methanol and orange oil induction reduced the NO emission and increased HC and CO emissions. With hydrogen induction, hydrocarbon and carbon monoxide emissions were significantly reduced. The heat release curve showed higher premixed rate of combustion with all the inducted fuels mainly at high power outputs. Addition of oxygenates like diethyl ether and dimethyl carbonate in different proportions to jatropha oil also improved the performance of the engine. It is concluded that dual fuel operation with jatropha oil as the main injected fuel and methanol, orange oil, and hydrogen as inducted fuels can be a good method to use jatropha oil efficiently in an engine that normally operates at high power outputs. Methyl ester of jatropha oil can lead to good performance at part loads with acceptable levels of performance at high loads also. Orange oil and methanol can be also blended with jatropha oil to improve viscosity of jatropha oil. These produce acceptable levels of performance at all outputs. Blending small quantity of diethyl ether and dimethyl carbonate with jatropha oil will enhance the performance. Diethyl ether seems to be the better of the two.