An Investigation of the Effect of Split Injection in Reduction of Pollutants Emitted from MT4.244 Diesel Engine

The aim of this paper is to investigate the possibility of simultaneous reduction of soot and NOx emissions in a direct injection diesel engine, using split injection method. For showing the effect of applying this injection system on pollutants of MT-4.244 DI diesel engine, the three-dimensional AVL_FIRE_CFD software was used. It was assumed that the engine was working under full-load condition and engine speed was 2000 rpm. First, the results of the simulation in single injection mode were validated, using the base state experimental data to find the base single injection mode. Then, different split injection modes were considered, in which the effects of pre-injection and postinjection were investigated by changing the mass of fuel in each pulse of injection. The effects of varying dwell time between injection pulses was analyzed as well. Then, the results of different split injection modes were compared with the base single injection one and finally the optimum mode of injection and optimum dwell time between injection pulses were selected. According to the results, the optimum injection mode for this engine for simultaneous reduction of soot and NOx emissions was achieved by injecting 75 percent of fuel in first pulse and 25 percent in the second with dwell time of 25 crank angle degrees between injection pulses.