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Abstract
Straight vegetable oil utilization as diesel engine fuel has the advantage of eliminating the energy, time, and cost involved in biodiesel production. Since straight vegetable oils have relatively higher viscosity compared to mineral diesel, they have to be modified to bring their combustion related properties closer to mineral diesel. In this study, a heat exchanger was used to utilize the waste heat of engine exhaust gas for reducing the viscosity of jatropha oil, and the performance, emission, and combustion characteristics are described in the first part of the paper. Carbon deposits, wear of vital engine parts, and the effect of jatropha oil on lubricating oil properties were analyzed in long-term endurance test for 512 h. The effect on lubricating oil of heated jatropha oil (J100) as well as 50 % blend of jatropha oil (J50) were compared with mineral diesel by comparing the lubricant’s density, viscosity, flash point, carbon residue, ash content, copper corrosion, and pentane and benzene insoluble measurements after an interval of every 128 h. Wear of the cylinder liner, diameter of piston, piston rings, gudgeon pin, and small and big-end bearings for J100 and J50 were measured vis-à-vis mineral diesel. Jatropha oil fuelled engine first undergoes lowering of lubricating oil viscosity followed by severe vegetable oil initiated oxidation of lubricating oil base-stock and thus the life of the lubricating oil gets depleted in approximately 400 h. The wear of J50 fuelled engine liner is found to be relatively lower compared to mineral diesel fuelled engine.
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