Effect of Injection Timing on Performance Parameters of Direct Injection Diesel Engine with Air Gap Insulation

Experiments were carried out to evaluate the performance of diesel engine with air gap insulated low heat rejection (LHR–2) combustion chamber consisting of air gap insulated piston with 3 mm air gap, with superni (an alloy of nickel) crown, air gap insulated liner with superni insert with neat diesel with varied injection timing. Performance parameters [brake thermal efficiency, exhaust gas temperature, coolant load, volumetric efficiency and sound levels,] were determined at various values of brake mean effective pressure (BMEP) of the LHR-2 combustion chamber and compared with neat diesel operation on conventional engine (CE) at similar operating conditions. The optimum injection timing was found to be 31obTDC (before top dead centre) with conventional engine, while it was 29o bTDC for engine with LHR-2 combustion chamber with diesel operation. Engine with LHR-2 combustion chamber with neat diesel operation showed deteriorated performance at manufacturer’s recommended injection timing of 27 o bTDC, and the performance improved marginally with advanced injection timing of 31obTDC in comparison with CE at 27obTDC.