Experimental Investigations of an IC Engine Operating with Alkyl Esters of Jatropha, Karanja and Castor Seed Oil

Abstract

Diesel engines are efficient systems popularly used to meet electricity and other power requirements for agriculture, industry, transportation and decentralized power generation. Vegetable oils can be successfully used in Compression Ignition (CI) engine either through engine modifications or fuel modifications, later being more feasible option. Fuel modification options include blending of vegetable oils with mineral diesel, transesterification, cracking/pyrolysis, micro-emulsion, and hydrogenation to reduce polymerization and viscosity, transesterification of vegetable oil with a short chain alcohol i.e. methanol or ethanol being most popular. Several non-edible plant oils have been found to be promising crude oils for the production of biodiesel. Methanol is most commonly used in commercial production of biodiesel. Fatty acid alkyl esters (FAAE) produced from higher alcohols is of interest as they may have different fuel properties in comparison to methyl or ethyl esters. In the present investigations, preparation of methanol, ethanol, propanol and butanol were used for formation of alkyl esters of Jatropha, Karanja and Castor. The composition of Jatropha, Karanja and Castor oil were analysed and alcoholysis process for preparing alkyl esters of Jatropha, Karanja and Castor oil with various alcohols was optimised. Alkyl ester-diesel blends were used to test the diesel engine at different load conditions and extensive performance and emissions studies were conducted in single cylinder direct injection compression ignition engines. It is concluded that lower blends of ethyl, propyl and butyl esters of Jatropha and Karanja feedstock have physico-chemical properties similar to methyl esters. However, deviation from the properties became larger for higher blending ratio. Therefore, in order to get engine performance in close range of diesel, the optimum blending ratio of higher alkyl esters need to be even less than methyl esters. Lower blends of higher alkyl esters are expected to give engine characteristics in close proximity to diesel overcoming the limitations of bio-diesel, while retaining the advantages.