Investigation on combustion performance and emission characteristics of a DI (direct injection) diesel engine fueled with biogas–diesel in dual fuel mode

In this research work, biogas was produced by the anaerobic digestion of non-edible de-oiled cakes obtained from oil crushing units. Further, the biogas was used as an alternative gaseous fuel in a DI (direct injection) diesel engine, in the dual fuel mode. Diesel was used as an injected fuel and biogas was inducted through the intake manifold, at four different flow rates, viz., 0.3 kg/h, 0.6 kg/h, 0.9 kg/h and 1.2 kg/h, along with the air. The combustion, performance and emission characteristics of the engine in the dual fuel operation were experimentally analyzed, and compared with those of diesel operation. The results indicated that, the biogas inducted at a flow rate of 0.9 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 is found to be longer than that of diesel throughout the load spectrum. The cylinder peak pressure in the dual fuel operation is found to be overall higher by about 11 bar than that of diesel operation. The NO (nitric oxide) and smoke emissions in the dual fuel operation are found to be lower overall by about 39% and 49%, compared to that of diesel operation.