COMPARISON OF ENGINE PERFORMANCE AND EMISSIONS FOR PETROLEUM DIESEL FUEL, YELLOW GREASE BIODIESEL, AND SOYBEAN OIL BIODIESEL

Abstract

Biodiesel is a nontoxic, biodegradable and renewable alternative fuel that can be used with little or no enginemodifications. Biodiesel is currently expensive but would be more cost effective if it could be produced from lowcost oils(restaurant waste, frying oils, animal fats). These lowcost feedstocks are more challenging to process because they containhigh levels of free fatty acids. A process for converting these feedstocks to fuelgrade biodiesel has been developed anddescribed previously. The objective of this study was to investigate the effect of the biodiesel produced from high free fattyacid feedstocks on engine performance and emissions. Two different biodiesels were prepared from animal fatbased yellowgrease with 9% free fatty acids and from soybean oil. The neat fuels and their 20% blends with No. 2 diesel fuel were studiedat steadystate engine operating conditions in a fourcylinder turbocharged diesel engine. Although both biodiesel fuelsprovided significant reductions in particulates, carbon monoxide, and unburned hydrocarbons, the oxides of nitrogenincreased by 11% and 13% for the yellow grease methyl ester and soybean oil methyl ester, respectively. The conversion ofthe biodiesel fuels energy to work was equal to that from diesel fuel.