Influences of biodiesel fuels produced from highly degraded waste animal fats on the injection and emission characteristics of a CRDI diesel engine

Abstract

In the current study, biodiesel fuels produced from waste chicken fat and wastefleshing oil with high free fatty acid were tested in a four stoke, four-cylinder,water-cooled, turbocharged-intercooled, common rail direct injection (CRDI)diesel engine. Their effects on the injection and exhaust emissioncharacteristics of the test engine were determined and compared with those ofpetroleum-based diesel fuel (DF) as the reference fuel. Engine tests wereperformed at different engine loads and constant engine speed of 2000 rpm.Injection characteristics showed differences with respect to engine load andfuel type. However, the effects of biodiesel fuels on the injection profiles weremore dominant for main injection characteristics such as the start of maininjection, end of the main injection, injection amount and injection rate andthese effects became more pronounced with increasing engine load. Comparedto DF, animal fat based biodiesels had better total hydrocarbon (THC) andcarbon monoxide (CO) emissions, but their carbon dioxide (CO2) andespecially nitrogen oxides (NOx) emissions were higher. In addition, wastefleshing oil-based biodiesel fuel emitted lower emissions than waste chickenfat-based biodiesel.