Vegetable oils can be directly used in compression ignition engines without any modification. A dual fuel engine was run using vegetable oils as primary and pilot fuels. Small quantities of orange oil were inducted along with air and ignited after compression by a pilot spray of Jatropha oil. The energy share of orange oil was varied till 35% of the total. Methyl ester of Jatropha oil and diesel were also used as pilot fuels for comparison.
Dual fuel operation with orange oil induction reduced the smoke level and improved the thermal efficiency with all pilot fuels. However, hydrocarbon and carbon monoxide emissions were higher. Ignition delay was also increased. Methyl ester of Jatropha oil showed inferior performance than diesel. Performance with Jatropha oil was still inferior. On the whole it is concluded that the use of Jatropha oil and methyl ester of Jatropha oil as pilot fuels and orange oil as the inducted fuel will lead to reduced smoke levels and improved thermal efficiency.