Performance Evaluation of Low Heat Rejection Diesel Engine with Pure Diesel

Investigations are carried out to evaluate the performance of a low heat rejection (LHR) diesel engine consisting of air gap insulated piston with 3­mm air gap, with superni (an alloy of nickel) crown, air gap insulated liner with superni insert and ceramic coated cylinder head with pure diesel operation with varied injection timing and injection pressure. Performance parameters are determined at various magnitudes of brake mean effective pressure. Pollution levels of smoke and oxides of nitrogen (NOx) are recorded at the peak load operation of the engine. Combustion characteristics of the engine are measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure­crank angle software package. Zero dimensional, multi­zone combustion model is assumed to predict combustion characteristics and validated with experimental results. LHR engine showed deteriorated performance at recommended injection timing and pressure and improved performance at advanced injection timing and higher injection pressure, when compared with conventional engine (CE). At peak load operation, brake specific fuel consumption (BSFC) decreased by 12%, while smoke levels by 16% and NOx levels increased by 34% with LHR engine at an injection timing of 32 o bTDC (before top dead centre) and an injection pressure of 270 bars, in comparison with CE operating at an injection timing of 27 o bTDC, and an injection pressure of 190 bars.