Advantaged performance of tractor engine fuelled with dewaxed-degummed jatropha oil on long-run evaluation under loads

Abstract

A tractor engine was fuelled with blends of dewaxed-degummed jatropha oil and diesel up to 50:50 (v/v) ratio. Higher power was obtained with treated oil than raw oil for all fuel blends. The engine operated well up to the blend ratio of 30:70 with treated oil and then there was sudden drop in engine speed under overload conditions. It was also found that there was sharp power drop with treated oil for the blends above 20 per cent, and hence the blend ratio of 20:80 (treated jatropha oil: diesel) was optimized for long duration operation. Power increase of 11.8 per cent with treated oil over raw oil was obtained at rated speed with optimized blend ratio, in spite of 5.5 per cent power drop with treated oil over diesel due to lower calorific value of plant oil. There was 2.8 per cent increase in torque with treated oil than raw oil. Brake thermal efficiency reduced with the percentage of plant oil in the blend and there was 2.5 per cent reduction with treated oil over diesel. A saving of 4.3 per cent in specific fuel consumption was achieved by using treated oil over raw oil. While CO, CO₂, and HC decreased with blend ratio up to 25 per cent and then increased, NO and NO2 increased with blend ratio. The SO₂ reduced with the increase in blend ratio due to the fact that plant oil contains no sulphur. There was no significant difference in smoke density between operation of engine with diesel and 20:80 blend at rated engine speed. Noise level and mechanical vibration had declining trend with the treated oil up to 25 per cent blend. There was no adverse effect with the operation of tractor engine up to 200 h during long-run evaluation with optimized blend (20:80). Operation of tractor with treated jatropha oil is encouraging in spite of slight hike (7.3%) in cost of operation with respect to decrease in CO, CO₂, HC, and SO₂. The study revealed that treated jatropha oil has promising potential as a fuel substitute up to 20 per cent blending in diesel.