Assessment of diesel engine performance, emissions and combustion characteristics burning biodiesel blends from jatropha seeds

The consumption rise and environmental impact of diesel fuel led to the use of non-edible oils as alternative fuels. Different extraction processes as screw, soxhlet, solvent and hydraulic were investigated to show their effects on the properties and fatty acid composition of the oil from Egyptian jatropha seeds. Screw press extraction was characterized because of its higher oil yield and improved properties. Biodiesel was blended with diesel oil in volumetric ratios of 20, 40, 60, 80 and 100 % as B20, B40, B60, B80 and B100. Tests were performed at 75 % of the engine load and different engine speeds. The maximum decreases in output brake power and volumetric efficiency for B100 were 27 and 9 %, respectively but the maximum decrease in thermal efficiency for B100 was 33 % compared to diesel oil at 75% of engine load. The highest increase of NO_X emission for B100 was 47 % at 75% of engine load about diesel oil. The maximum decline in smoke emission for B100 was 22 % about diesel oil at 75% of engine load. Cylinder pressures and heat release rate values of biodiesel blends were lower than crude diesel. Extracted oil by screw press was selected to be a biodiesel feedstock because of its improved physical and chemical properties. Lower volume percentages of biodiesel up to 20 % are recommended as alternative fuels due to near performance, emissions and combustion characteristics of diesel oil.