PRODUCTION AND EVALUATION OF BIODIESEL FROM MARULA (Sclerocarya

Abstract

Reducing dependence on fossil fuel, environmental pollution and depletion of fossil oil well stimulated active researchers’ interest to look for an alternative. Biodiesel from sclerocarya birrea (marula oil) is one of many possible feedstock to reduce dependence on fossil oil and depletion of fossil oil well. In this study marula biodiesel with B10, B20, B30, B40, B50, B60 and B100 were prepared to be used as a fuel in a TD 110-TD 115 single cylinder four-stroke compression ignition engine test bed, and incorporated with a hydraulic dynamometer. The marula oil with methanol in ratio 6:1 and potassium hydroxide catalyst of concentration of 1.4 wt% were heated in a hot plate-magnetic stirrer for 30 minutes at a temperature of 60 0C and operated at a speed of 305.5 rpm. The most common properties of the marula biodiesel were determine using standardized laboratory methods of the Association of Official and Analytical Chemist. The oil yield of the marula was found to be 58.7%. From the test it shows that the brake torque and brake power generated increase to the maximum value of 13.52 Nm and 2.55 kW respectively at 2500 g engine load for B10. The maximum brake specific fuel consumption and brake specific energy consumption was recorded at the engine load of 2500 g with B30 fuel sample lower than conventional diesel. The saponification value, iodine value, for marula oil are 187.72 mgKOH/g and 61.77 gl/100g respectively. Free fatty acid, acid value, peroxide value, cetane number, density, viscosity, calorific value, flash point, and pour point for both marula oil and marula biodiesel were found to be 1.72 and 0.21%, 3.42 and 0.44 mgKOH/g, 10.67 and 2.4 meq/kg, 51 and 55.1,943 and 850 kg/m3, 41 and 5.0 mm2/sec, 38.40 and 42.89 MJ/kg, 240 and 175 ℃ and 5 and 3 ℃ respectively. Thus, the results of the analysis falls within the specification range of international standards for biodiesel specifications. The engine emits less CO, CO2 and HC emission compare to that of diesel fuel under all loading conditions. With increase in biodiesel percentage CO, CO2 and HC emissions level decreases due to oxygen content in biodiesel which helps complete combustion. The NOx emission trends for all the fuel samples increased with increase in load and increase in MOME percentage in the diesel fuel.