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RCCI strategy gained popularity in automotive applications due to lower fuel consumption, less emissions formation and higher engine performance in compared with other diesel combustion strategies. This study presents results of an experimental and numerical investigation on RCCI combustion using natural gas as a low reactivity premixed fuel with advanced injection of diesel fuel as a high reactivity fuel in a CI engine. An advanced three dimensional CFD simulation coupled with chemical kinetic developed to examine the effects of diesel injection timing, diesel/natural gas ratio and diesel fuel included spray angle on combustion and emissions formation in various engine loads and speeds, in a heavy duty diesel engine.

In this paper, reduced temperature combustion has been investigated at high load condition of a direct injection diesel engine. A three dimensional CFD model for flow field, spray, spray-wall interactions, combustion and emissions formation processes have been used to carry out the computations. The combined effect of EGR temperature and EGR rate is analyzed to choose by consideration of engine performance. Then, the effect of injection timing and injection pressure is investigated to the improvement of mixture formation at high engine load condition. It reveals that combustion temperature is dramatically decreased by the increase of cold EGR to 25% rate. This characteristic influences on the increase of the liquid spray penetration and the decrease of indicated mean effective pressure (IMEP) and NOx emission associated with the increase of soot emission.