Comparative studies on Performance, Emissions and Combustion Characteristics of Jatropha Oil in Crude Form and Biodiesel in a Medium Grade Low Heat Rejection Diesel Engine

Experiments were carried out to evaluate the performance of a medium grade LHR diesel engine consisting of air gap insulated piston with 3-mm air gap, with superni (an alloy of nickel) crown and air gap insulated liner with superni insert with different operating conditions of jatropha oil in crude from and biodiesel form with varied injection timing and injection pressure. Performance parameters of brake thermal efficiency (BTE), exhaust gas temperature (EGT) and volumetric efficiency (VE) were determined at various values of brake mean effective pressure (BMEP). Exhaust emissions of smoke and oxides of nitrogen (NOx) were recorded at different values of BMEP. Combustion characteristics were measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure-crank angle software package. In comparison with CE with diesel operation, biodiesel operation on CE showed compatible performance while LHR engine showed improved performance. The performance of both version of the engine improved with advanced injection timing and higher injection pressure with test fuels. Peak brake thermal efficiency increased by 11%, at peak load operation-brake specific energy consumption decreased by 6%, exhaust gas temperature decreased by 25C, volumetric efficiency decreased by 5%, smoke levels were compatible and NOx levels increased by 35% with biodiesel operation on LHR engine at its optimum injection timing (31bTDC), when compared with pure diesel operation on CE at manufacturer’s recommended injection timing (27bTDC).