COMBUSTION AND EMISSIONS FORMATION CONTROL IN REACTIVITY CONTROLLED COMPRESSION IGNITION (RCCI) ENGINES WITH VARIOUS FUELS

Abstract

At first, a multi-component reaction mechanism, which could realize dual-fuel combustion of gasoline and diesel/biodiesel, was developed and validated under various conditions. Then this newly developed mechanism was integrated into KIVA4-CHEMKIN to reveal the role of reactivity gradient of RCCI combustion. It is found that reactivity gradient could retard the ignition timing, lower heat release rate, and reduce NOx and soot emissions. In addition, modellings were conducted on gasoline and biodiesel fueled RCCI engine to investigate the effects of fuel ratio, start of injection (SOI) timing and piston bowl geometry. Results show that more premixed gasoline, advanced SOI timing and SCC bowl geometry can bring out better performance and lower NOx and soot emissions. At last, a systematic approach with the sequence of fractional factorial design, f-T map analysis and full factorial design, was applied to find the high efficiency and low emissions operating conditions of an RCCI engine.