Methyl ester of Sal oil (Shorea robusta) as a substitute to diesel fuel-A study on its preparation, performance and emissions in direct injection diesel engine

Many research reported vegetable oil as a potential substitute for diesel engines with its ester form known as biodiesel. The biodiesel can be prepared by different process using vegetable oil and alcohol. The common process used for biodiesel preparation is known as transesterification. This paper presents the transesterification of Sal oil (Shorea robusta) into Sal oil methyl ester (SOME) and its performance in direct injection diesel engine. Several process parameters such as catalyst quantity, molar ratio of alcohol, reaction temperature and reaction time were studied and the optimized process conditions are amount of catalyst (NaOH) - 0.25 wt%, alcohol (methanol) - 150% excess, reaction temperature - 65 degrees C and reaction time - 1.5 h. The studies with SOME as fuel in the direct injection diesel engine shows that the exhaust emissions such as CO, HC and NOx are reduced by 25%, 45% and 12%, respectively compared to diesel without significant difference in thermal efficiency. Based on this study it is concluded that the SOME can be used as fuel without any modifications in the engine and hence this biodiesel can be a potential substitute to standard diesel fuel. (C) 2011 Elsevier B.V. All rights reserved.