Comparative performance analysis of marula oil and petrodiesel fuels on a variable compression ratio engine

Abstract

The quest for biofuel production and use in Botswana is driven by factors including volatile oil prices, need for fuel security, potential for job creation, potential reduction in greenhouse gas emissions, and economic diversification. In line with national efforts to come up with energy sources that are both environmentally friendly and sustainable, this work was carried out to compare performance properties of native marula seed oil and petrodiesel fuels on a variable compression engine test rig with automatic data acquisition set up. Parameters such as engine torque, brake power and specific fuel consumption were measured at different loads for the two fuels. The results indicated that engine performance when powered with marula oil as fuel was very close to that when powered with petrodiesel. The engine performance was also analysed for same parameters of engine torque, brake power and specific fuel consumption when powered by the same two fuels over varying compression ratios at a fixed load of 80%. The results indicated that compression ratio of 16:1 yields optimum performance in terms of engine torque and brake power for both petrodiesel and marula oil fuels; marula oil fuel has a smooth rising performance profile across all compression ratios which out-performs petrodiesel on lower compression ratios for engine torque and brake power, and is largely better than petrodiesel on fuel consumption.