Effect of nozzle opening pressure on combustion, performance, and emission analyses of a dual fuel diesel engine

In this study, a single cylinder, four stroke, air cooled, direct injection (DI) diesel engine developing a power of 4.4 kW at a constant speed of 1500rpm was modified to operate on a dual fuel mode running on raw biogas-Waste cooking oil methyl ester (WCOME); where, WCOME was used as a pilot fuel to initiate combustion, while biogas was used as a primary fuel which proceeded throughout the engine operation. For the dual fuel operation, the effect of nozzle opening pressure of the fuel injector was varied from the original nozzle opening pressure of 200 bar to 280 bar at a regular interval of 20 intervals. Also, the engine load in terms of power output was varied from 0 to 4 kW in steps of 1 kW. The combustion, performance, and emission analyses of the engine run on the dual fuel operation at different nozzle opening pressure were compared with those of the normal diesel operation at different loads. The test results indicated that, thermal efficiency increased by about 4.6% for 240 bar at full load. In the dual fuel operation, NO emission increased with the increase in the nozzle opening pressure, however, NO emission was still lesser than that of the diesel operation. From the obtained results, it is suggested that, a nozzle opening pressure of 240 bar can be considered as an optimum condition for the tested engine which was run biogas-WCOME on a dual fuel mode.