Experimental and Numerical Study of Diesel HCCI Combustion by Multi-Pulse Injection

Diesel-fueled HCCI combustion was achieved by multi-pulse injection before top dead center (TDC). However, the multi-pulse injections strategies have not been sufficiently studied previously due to the large number of parameters to be considered. In the present work, a series of multi-pulse injection modes with four or five pulses in each mode are designed, and their effects on diesel HCCI Combustion are experimentally studied. The results showed that the HCCI diesel combustion was extremely sensitive to injection mode. There were many modes to achieve very low NOx and smoke emissions, but the injection parameters of these modes must be optimized for higher thermal efficiency.

A micro-genetic algorithm coupled with a modified 3D engine simulation code is utilized to optimize the injection parameters including the injection pressure, start-of-first-injection timing (SOI), fuel mass in each pulse injection and dwell time between consecutive pulse injections. The results showed that the optimized injection strategy could offer a large decrease in BSFC levels for very low NOx and soot levels.