A COMPARATIVE ANALYSIS OF THERMAL PERFORMANCE AND EMISSION CHARACTERISTICS OF METHYL ESTERS OF KARANJA AND JATROPHA OILS BASED ON A VARIABLE COMPRESSION RATIO DIESEL ENGINE

The present experimental investigation is concerned with the comparative evaluation of karanja and jatropha methyl esters (biodiesel) as an alternative fuel in a diesel engine based on the thermal performance and emission characteristics. The experiments are conducted on a single-cylinder, four-stroke, direct-injection, variable compression ratio (CR), and compression ignition engine and the experimental parameters considered include the engine torque, injection pressure, and CR. Comparative measures of brake thermal efficiency (BTHE), brake specific fuel consumption (BSFC), exhaust gas temperature, smoke opacity, and HC, CO, and NOX emissions are presented and discussed. It is observed that, at full torque, BTHE is lower by 4.4% and 4.5% and BSFC is higher by about 6% and 15% for karanja and jatropha biodiesel, respectively, compared to that of diesel. At a torque of 20 Nm, CO emission levels for karanja are higher by 9% compared to jatropha but lesser by about 11% in comparison with that of diesel. Results show that thermal performance of the engine fuelled with both the biodiesels is generally comparable to that when the engine is fuelled with pure diesel. At higher compression ratios, the engine fuelled with both the biodiesels gives lesser emissions and better performance compared to that of diesel.