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

Abstract

Homegeneous charge compression ignition (HCCI) combustion canachieve very low NOx and soot emissions but knocking and misfiringrestrict the operating range of this kind of engines. In this work, n-butanolwhich has low reactivity and high volatility blended with n-heptane thatchoosen as reference fuel in this study with various rates (25 vol% and 50vol%). 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. theparameters such as in-cylinder pressure, heat release rate, CA10, ringingintensity, thermal efficiency, brake torque, power output, specific fuelconsumption, and HC and CO emissions were determined. The resultsshowed that both in-cylinder pressure and heat release rate decreased withincreasing lambda. Increasing amount of n-butanol in the charge mixtureresulted a decrease both in-cylinder pressure and heat release rate. nbutanol also provided retarded combustion phasing and increased CA10.Ringing intensity decreased with increasing both lambda and n-butanolcontent in the mixture. Thermal efficiency increased with n-butanol. HCand CO emissions increased with increasing lambda. HC and CO emissionsincreased with increasing amount of n-butanol in the charge mixture.Operating range of HCCI engine was expanded with n-butanol in bothknocking and misfiring zones.