Effects of mixing and chemical parameters on thermal efficiency in a partly premixed combustion diesel engine with near-zero emissions

Abstract

A hybrid combustion control strategy in a partly premixed combustion diesel engine have been developed and carefully optimized for high thermal efficiency and near-zero emissions in a wide engine operation range, up to a gross indicated mean effective pressure of 1.1 MPa. The mixing and chemical control parameters of combustion include fuel injection timing, injection rate pattern (such as multi-pulse injections), boost pressure, exhaust gas recirculation and in-cylinder temperature, regulated by the timing of intake valve closing. The interaction of the control parameters plays a decisive role in the determination of thermal efficiency and exhaust emissions, which are investigated by means of a comparison analysis with sweeping control parameters and data statistics. It is also found that thermal efficiency is more sensitive to combustion control parameters than emissions in clean partly premixed combustion.