Bio-fuel production from animal fats and experimental investigation of its usage in a diesel engine

In this study, animal tallow methyl ester as biodiesel fuel was produced from inedible animal tallow by base-catalyzed transesterification. Viscosity and density of tallow methyl esters are found to be very close to that of diesel. The calorific value of biodiesel is found to be slightly lower than that of diesel. However, viscosity and density of methyl ester have been found to meet ASTM D6751 and EN 14214 specifications. An experimental study was carried out in order to investigate the performance and emission characteristics of tallow methyl ester (B100) and its blends with petroleum diesel fuel (B5, B20, B50) in a direct injection diesel engine and compare the findings with petroleum diesel fuel. The effective engine power was comparable by biodiesel and blend fuels compared with diesel fuel. It was observed that the addition of biodiesel to the diesel fuel decreases the effective efficiency of engine and increases the specific fuel consumption. Emissions of CO, NOx, SO2, CO2 and smoke were reduced around 15%, 38.5%, 72.7%, 16.7% and 56.8%, respectively, in case of tallow methyl esters (B100) compared to diesel fuel. Besides, the lowest CO and NOx emissions were obtained for B20 among all test fuels. In order to clarify the effect of biodiesel on engine components and whether it is suitable for long term use or not in diesel engines, the engine was operated with both B20 and diesel fuel for 100 hours. Deposits in engine components were comparable in amount, but slightly different in color and adhesive, with the B20 when compared with those of diesel fuel. Besides, formation deposits in engine were not prevent to engine operated that engine was satisfactorily operated for 100 hours. It is concluded at the results of short and long term engine experiments, biodiesel and blended fuels can be used in direct injection diesel engines without any modification to substitute diesel fuel. The reductions in exhaust emissions made especially B20 a suitable alternative fuel for diesel engines and thus could help in controlling air pollution.