Abstract:
Karanja (Pongamia pinnata) oil, a non-edible high viscosity (27.84 cSt at 40°C) straight vegetable oil, is blended with conventional diesel in various proportions to evaluate the performance and emission characteristics of a single cylinder direct injection constant speed diesel engine. Diesel and karanja oil fuel blends (B5, B10, B15, B25, and B30) were used to conduct short-term engine performance and emission tests at varying loads ( 20%, 40%, 60%, 80%, and 100%). Tests were carried out over the entire range of engine operation and engine performance parameters such as fuel consumption, thermal efficiency, exhaust gas temperature, and exhaust emissions were recorded.
The brake thermal efficiency (BTE), brake specific energy consumption (BSEC), and exhaust emissions were evaluated and compared with diesel fuel determine the optimum fuel blend. A fuel blend of 10% karanja oil (B 10) showed higher BTE at a 60% load as compared with other blends but it is slightly lower than diesel. Similarly, the overall emission characteristics were found to be best for the case of B10 over the entire range of engine operation.
Exhaust gases emission were measured with the help of AVR 2 gas analyzer. The temperature of exhaust gases coming out of the engine gives an indication of the thermal efficiency of the engine. Heat loss is important for engine as it leads to lower working temperature and ultimately to reduced efficiency. The combustion is supposed to be completed at the end of the constant pressure burning, however in actual practice it continues up to about half of the expansion stroke. In general about 30 per cent of the energy supplied to diesel engine is lost as exhaust heat. The exhaust gas temperature depends upon the fuel-air ratio and combustion characteristics of the fuel, which in turn may depend upon the type of fuel and loading conditions as well as engine compression ratio and injection timing.
