The effects of intake temperature on reactivity controlled compression ignition combustion under high load

Abstract

In order to improve of high loaded diesel engine with high ethanol substitution rate, the effects of intake temperature on the combustion characteristics and generation characteristics of pollutants in cylinder from reactivity controlled compression ignition (RCCI) engine under high load was studied numerically. RCCI experimental data were obtained from a four cylinder turbocharged diesel engine fuel modified to run with diesel/ethanol dual fuel in the study. The simulation was performed via converge computational fluid dynamics (CFD) code, and numerical results were validated with the experimental data. The parameters such as cylinder pressure, cylinder temperature, heat release rate (HRR), CA10, CA50, indicated thermal efficiency, maximum pressure rise rate, NOx, soot, HC and CO emissions were investigated at 2000 rpm engine speed and high engine load (80% full load). The results show that decreasing intake temperature reduces the peaks of cylinder pressure and cylinder temperature, the HRR profile changes from double peak to single peak; the CA10 and the CA50 is retarded; maximum pressure rise rate and indicated thermal efficiency decrease. In addition, with the decreasing of intake temperature, the peaks of NOx, soot and CO generated in cylinder decreases, while the peaks of unburned HC generated in cylinder almost remain constant. Thus it can be seen that using optimal intake temperature is an effective way to improve ethanol substitution rate of diesel engine under high load.