Abstract
In this study, the combustion efficiency and performance of an engine using biodiesel produced from rubber seed oil (RSO) was compared with petroleum diesel. The tests were performed at full load over a range of engine speeds in a single cylinder, direct injection diesel engine. The experimental results show that the RSO biodiesel resulted in better combustion than with the petroleum diesel at low to medium engine speeds (1300–1900 rpm). In this range, the combustion efficiency and the brake fuel conversion efficiency of the RSO biodiesel were found to be 1.03% and 7.33% higher respectively than those of petroleum diesel. In addition, a slightly lower brake specific CO2 emission level was achieved, this being because of the higher H/C ratio of the RSO biodiesel. A major improvement in the brake specific CO emission of the RSO biodiesel was found, these being 55% lower than those of the petroleum diesel. However, the brake specific NOx emission was 39.5% higher. Both the brake torque and brake power of the RSO biodiesel were 4.91% lower than those of the petroleum diesel while an increase of around 6.84% fuel consumption was required at the same power output all these being due to its lower heating value. Above 1900 rpm in these tests, the combustion efficiency trend reversed with the RSO biodiesel giving a lower value than the petroleum diesel. In this higher speed range, the performance (i.e. brake fuel conversion efficiency, brake power, and brake torque) fell below that of the petroleum diesel with the brake specific fuel consumptions and the brake specific CO emissions being higher.