Experimental Study of Biogas Production & its Utilization in CI Engine in Dual Fuel Mode

Abstract

In this research work, biogas was produced by the anaerobic co-digestion of cow dung with yard waste. First a laboratory scale experiment was conducted to find the best blend ratio of cow dung and yard waste which maximize the biogas production. Mechanical pre-treatment of feedstock was done to increase the specific surface area and increase the amount of biogas production. It was found that, with 75% cow-dung and 25% yard-waste (by volume) the biogas production was maximum. Further, using that optimum ratio large scale biogas production was done. The biogas was used as primary fuel and diesel as pilot fuel, in a direct injection(DI) diesel engine in dual fuel mode. Biogas was inducted through the intake manifold, at four different flow rates, viz., 0.25 kg/h, 0.5 kg/h, 0.75 kg/h and 1 kg/h, where it mixes with the air and goes to the cylinder in the suction stroke. Diesel was injected directly to the engine cylinder at the end of the compression stroke. The combustion, performance and emission characteristics of the engine in the dual fuel operation were experimentally analysed, and compared with those of diesel operation. The results indicated that, the biogas inducted at a flow rate of 0.75 kg/h was found to give a better performance and lower emission, than that of the other flow rates. The ignition delay in the dual fuel operation was found to be longer than that of diesel throughout the load spectrum. The cylinder peak pressure in the dual fuel operation was found to be overall lower than that of diesel operation. The nitric oxide(NO) and smoke emissions in the dual fuel operation are found to be decreased, compared to that of diesel operation.