Biodiesel production from free fatty acids and the effects of its blends with alcohol–diesel on engine characteristics

In this experimental study, biodiesel production from free fatty acids of soybean oil and the effects of its blends with alcohol–diesel on diesel engine performance and exhaust emissions were studied. Crude glycerine was neutralized to produce the free fatty acids. Methyl alcohol was reacted with the free fatty acids in the presence of acid catalyst to form biodiesel. Biodiesel, diesel, and alcohols were mixed at different volumetric ratios, and the properties of each blend were determined. The blends and diesel were tested in a single cylinder direct injection diesel engine at full-load conditions. In conclusion, torque and power characteristics of blends were found similar to those of diesel. Break specific fuel consumption of the blends slightly increased depending on lower heating values. CO and smoke emissions decreased up to 34.52 and 39.30 %, respectively. Although NO_x emissions increased with B50, it showed a downward trend with alcohol-containing blends.