Impact of fatty acid composition and physicochemical properties of Jatropha and Alexandrian laurel biodiesel blends: An analysis of performance and emission characteristics

This experimental investigation deals with the effects of fatty acid methyl ester (FAME) composition and the physicochemical properties of biodiesel on engine performance and emissions. FAME compositions have a considerable influence on the physical and chemical properties of biodiesel, such as density, viscosity, heating value, cetane number (CN), oxidation stability, and cold flow properties. The performance and emissions of a four-cylinder turbocharged diesel engine were studied under varying speeds and full load condition. For this investigation, 10% and 20% blends of Jatropha (Jatropha curcas), Alexandrian laurel (Calophyllum inophyllum), and palm biodiesels (JB, ALB, and PB, respectively) were used, and the results were compared with that of the B5 fuel (95% diesel and 5% palm biodiesel). The content of saturated fatty acid (methyl palmitate) for ALB and JB was found to be 23.3% and 20.4% higher respectively than that for PB. In total, PB showed 19.8% higher saturation than JB, while ALB showed 7.3% higher saturation than JB because of their higher content of longer chain saturated fatty acid (methyl stearate). The CNs of all three biodiesels increased with the increase of carbon chain length and saturation level, whereas iodine value and saponification value decreased with the increase of saturation level. An average of 2.8% and 4.5% brake power reduction were observed in the case of 10% and 20% biodiesel blends respectively. Brake specific fuel consumption increased in the range of 6%–20% compared with B5 fuel, whereas carbon monoxide and hydrocarbon emissions decreased significantly. Nitrogen oxide emissions increased in the range of 9%–23% for the 10% and 20% biodiesel blends with respect to B5 fuel.