Simulation Study on the Effects of Methane – Normal Heptane Blend Fraction on the Performance of a Reactivity Controlled Compression Ignition (RCCI) Engine

In this paper, the effects of intake temperature and methane energy ratio on emission and combustion phasing in reactivity controlled compression ignition (RCCI) engine have been numerically investigated. In this study, the natural gas injected from inlet port and diesel fuel injected in cylinder directly. For validation, the results of RCCI engine have been compared to experimental data. For this purpose, different parameters such as temperature and pressure in cylinder, rate of heat release rate, soot and NOx compared. Afterwards, the effects of temperature variation from 350 K to 380 K and methane energy ratio variation from 0.65 to 0.85 were studied. The results show that by increasing intake temperature the maximum of pressure, rate of heat release and NOx emission would increase significantly while soot emission decreases. Also by increasing methane energy ratio from 65% up to 85% in the constant intake temperature and pressure, the mixture octane number will be rise, which would lead to an increases in ignition delay up to 5 crank angle so IMEP as an important factor will be enhanced and also NOx emission decreases because of lower combustion temperature .Consideration of intake temperature and methane energy ratio shows this parameter can play an important role on controlling on combustion phasing.