Comparative study of engine oil tribology, wear and combustion characteristics of direct injection compression ignition engine fuelled with castor oil biodiesel and diesel fuel

In the present work the tribological evaluation of engine oil characteristics, engine wear and engine performance was carried out on a four-stroke single cylinder direct injection diesel engine operated using B20 castor oil biodiesel and diesel fuel separately. The castor biodiesel has very low cloud and pour point that show that this fuel is very suitable for using in extreme winter temperature. Both the engines were subjected to 150-hour long-term endurance test. The engine oil samples collected from the engine at regular intervals of 25 hours were subjected to tribological analyses, namely viscosity, flash and fire point, total acid number (TAN), soot, ash content, water content and wear debris analysis. It was observed that the castor oil methyl ester with diesel blend up to 20% (B20) does not affect the engine oil performance with respect to viscosity, TAN, soot and wear. The performance of castor oil biodiesel is found to be comparable to that of diesel fuel, and the additional lubricity of biodiesel fuel due to higher viscosity as compared to diesel fuel resulted in lower wear of moving parts and thus improved the engine durability.