The focus of this research was pointed at exploring technical feasibility of castor biodiesel with and without diethyl ether additives in direct injection compression ignition engines without any substantial hardware modifications. In this work, the methyl ester of castor oil with and without additives was investigated for its performance as a diesel engine fuel. Fatty acid methyl ester was produced via transesterification process using potassium hydroxide as a catalyst and purified castor oil which is extracted from the castor seed was used.

To obtain a high quality biodiesel fuel that comply the specification of standard methods, some important variables such as reaction temperature, molar ratio of methanol to oil and mass weight of catalyst were selected and studied. At the following optimum conditions; 60 °C of reaction temperature, 6:1 methanol to castor oil molar ratio, 1% catalyst concentration wt/wt%, reaction time of 90 minutes and 600 rpm agitating speed, an optimum fatty acid methyl ester yield of 92.08% was obtained, indicating that potassium hydroxide has the potential as a catalyst for the production of fatty acid methyl ester from castor oil.

The fuel samples were prepared by blending castor ethyl ester with diesel in the composition of B0, B10, B15, B20, B10DEE5, B15DEE5, and B20DEE5. Moreover, after preparation of the tested fuels only the kinematic viscosity were measured and the measured results were changed. For instance, kinematic viscosity changes in percent were 23.5%, 22.5% and 18.7% for B10DEE5, B15DEE5 and B20DEE5 respectively.

The performance parameters evaluated were break thermal efficiency (B.Th.), torque and power. The results of experimental investigation with biodiesel blends were compared with that of methyl ester and baseline diesel. The results indicate that the torque percentage variation of fuels with DEE additive increase with increase engine speed, this shows the percentage change of torque at lower speed is small, because even though the fuel has higher viscosity than B0 it has sufficient combustion time. At higher engine speed the percentage torque variation is higher; this is due to the high reciprocating motion of the piston the fuel cannot get sufficient time to be evaporated and combusted due to pure atomization.

The comparing power percentage difference between fuel with and without DEE to the neat diesel fuel, with DEE is less power difference than without DEE, this is due to DEE the fuel has less viscosity than without DEE, this increase atomization of fuel to easily burn in the combustion chamber.

The BSFC percentage difference which is compared to fuels with and without DEE to the neat diesel fuel,from this figures the difference between diesel fuel and with DEE adding fuel is smaller than without DEE fuels, this is due to DEE the fuel is atomized and easly burned this decreased the fuel consumption.   Furthermore, a single cylinder compression ignition engine was operated successfully using ethyl ester of castor oil as the soul fuel with acceptable performance.