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 waste fleshing 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 emission characteristics of the test engine were determined and compared with those of petroleum-based diesel fuel (DF) as the reference fuel. Engine tests were performed at different engine loads and constant engine speed of 2000 rpm. Injection characteristics showed differences with respect to engine load and fuel type. However, the effects of biodiesel fuels on the injection profiles were more dominant for main injection characteristics such as the start of main injection, end of the main injection, injection amount and injection rate and these effects became more pronounced with increasing engine load. Compared to DF, animal fat based biodiesels had better total hydrocarbon (THC) and carbon monoxide (CO) emissions, but their carbon dioxide (CO2) and especially nitrogen oxides (NOx) emissions were higher. In addition, waste fleshing oil-based biodiesel fuel emitted lower emissions than waste chicken fat-based biodiesel.