Utilization of Castor Oil-Based Ethyl Ester Biodiesel in a Diesel Engine

Biodiesel was prepared through transesterification of castor oil and ethanol. The optimization of parameters related to the yield of transesterification, such as oil to ethanol molar ratio, concentration of catalyst, reaction temperature and reaction time, was investigated. The results indicated that the optimum condition for castor oil ethyl ester (COEE) production was 1:12 oil to ethanol molar ratio, 1.5% catalyst concentration, 40 °C reaction temperature and 150 minutes reaction time. To avoid extremely high viscosity of castor oil which can affect the fuel injection system, COEE was blended with commercial diesel fuel at different concentrations ranged from 5%-15% volume and key properties of fuel blends, mainly focused on fuel lubricity and viscosity were evaluated. The presence of 8% COEE in diesel fuel was concluded as the optimum concentration because the smallest wear scar diameter was obtained after the lubricity test and its viscosity was within acceptable limits prescribed by the standard specification of diesel fuel. Consequently, the blend of 8% COEE and diesel fuel was selected in the engine test. The results showed that the addition of 8% COEE to diesel fuel can improve brake thermal efficiency and brake specific fuel consumption. Moreover, the reduction in carbonaceous gas emissions and oxides of nitrogen was obtained by the combustion of the COEE blend.