Numerical prediction of the performance, combustion and emission characteristics of a CI engine using different biodiesels

An attempt has been made to investigate numerically the energetic, combustion and environmental performances of a single-cylinder naturally aspirated direct injection diesel engine using the commercial software, Diesel-RK. Diesel and five different biodiesels, namely jatropha biodiesel, soybean biodiesel, palm stearin biodiesel, karanja biodiesel and rapeseed biodiesel, are used separately as fuels in this study. Experiments have also been conducted with diesel and palm stearin biodiesel to validate the predicted results. The experimental and the numerical results match both qualitatively and quantitatively with slight deviations. The analysis of the numerical results shows that the engine performance deteriorates with the use of different biodiesels as fuels. Brake thermal efficiency decreases by 3% (maximum) in case of palm stearin biodiesel. On the other hand, brake specific fuel consumption and brake specific energy consumption increase and the maximum values are found to be 25.8 and 3.6%, respectively. Among the biodiesels, jatropha biodiesel showed the best performance and palm stearin biodiesel showed the worst. When the combustion characteristics were compared, it was noted that both the ignition delay period and the heat release rate decrease to some extent for different biodiesels compared to diesel. The use of biodiesel gives a cleaner exhaust compared to that of diesel, and jatropha biodiesel gives the cleanest exhaust in terms of particulate matter and smoke emissions. However, the formation of nitrogen oxides increases with the use of biodiesels and the maximum increase was noted with rapeseed biodiesel.