Experimental Studies on the Jatropha-Biogas Dual Fuel Engine

In the current study, experiments were conducted on a compression ignition engine using neat vegetable oil (Jatropha oil) and biogas in the dual-fuel mode. A mono-cylinder, 4-stroke, direct injection, air-cooled diesel engine producing an output power of 4.4 kW at 1500 rpm was used to carry out the experiment. This engine was modified to operate in a dual fuel mode at 100% and 50% load conditions. From the result, the jatropha oil operation resulted in reduced thermal efficiency and increased smoke and hydrocarbon emissions. Brake thermal efficiency has been observed as 31% and 27% with neat-diesel fuel and jatropha oil respectively. While operating the engine in dual fuel mode, the thermal efficiency was observed to be inferior and increase in hydrocarbon emission, with a considerable reduction in smoke compared with single fuel operation. The key reason for lower thermal efficiency during dual fuel operation is mainly due to the presence of carbon dioxide in primary biogas fuel. Overall, it was concluded that adopting the dual fuel mode with vegetable oil as pilot fuel will result in reduced emissions and improvement in efficiency at medium and high outputs.