Combustion, performance and emission caracteristics of a HCCI engine fuelled with n-butanol/n-heptane blends

Homegeneous charge compression ignition (HCCI) combustion can achieve very low NOx and soot emissions but knocking and misfiring restrict the operating range of this kind of engines. In this work, n-butanol which has low reactivity and high volatility blended with n-heptane that choosen as reference fuel in this study with various rates (25 vol% and 50 vol%). The experiments performed at various engine speeds (800-1800) and lambda (λ=1.6-2.95) at full load and 60 oC inlet air temperature. the parameters such as in-cylinder pressure, heat release rate, CA10, ringing intensity, thermal efficiency, brake torque, power output, specific fuel consumption, and HC and CO emissions were determined. The results showed that both in-cylinder pressure and heat release rate decreased with increasing lambda. Increasing amount of n-butanol in the charge mixture resulted a decrease both in-cylinder pressure and heat release rate. n-butanol also provided retarded combustion phasing and increased CA10. Ringing intensity decreased with increasing both lambda and n-butanol content in the mixture. Thermal efficiency increased with n-butanol. HC and CO emissions increased with increasing lambda. HC and CO emissions increased with increasing amount of n-butanol in the charge mixture. Operating range of HCCI engine was expanded with n-butanol in both knocking and misfiring zones.