Experimental studies on combustion and emissions of RCCI fueled with n-heptane/alcohols fuels

Abstract

This paper presents an experimental study on combustion and emissions characteristics of reactivity controlled compression ignition (RCCI) combustion in which in-cylinder directly injected n-heptane combined with port injection (PI) of ethanol, n-butanol and n-amyl alcohol are used in a single-cylinder engine. The results show that when the overall lower heating values (LHVs) per-cycle is constant, with the increase of premixed ratio (RP), nitrogen oxides (NOx) and soot emissions decrease. When in high overall LHVs per-cycle, NOx and soot emissions of ethanol, n-butanol and n-amyl alcohol RCCI are also high. Meanwhile, compared to n-heptane/n-butanol and n-heptane/n-amyl alcohol, the combustion phases of ethanol RCCI are strongly delayed at high premixed ratio. For certain premixed ratios and overall LHVs per-cycle, low NOx and soot emissions can be realized when fueled with ethanol.