Impact of exhaust gas recirculation and split injection strategy combustion behavior on premixed charge compression ignition engine fuelled with moringa oleifera methyl ester

Abstract

Influence of split injection strategy of moringa oleifera methyl ester and its blends with exhaust gas recirculation on diesel engine combustion, performance and emission characteristics using common rail direct injection (CRDI) system were investigated in this work. In split injection strategy, the pilot (PIT) and main injection timings (MIT) were fixed between 35 °CA – 40 °CA bTDC and 15 °CA –25 °CA bTDC, respectively. The minimum and maximum nozzle opening pressure were fixed as 300 and 600 bar with an interval of 100 bar. In addition, 10% to 30% of EGR flow rate was introduced with an interval of 5%. Experimental results reveal that B100-10%-90% has achieved maximum brake thermal efficiency of 35% at PIT of 35 °CA bTDC, MIT of 25 °CA and NOP of 300 bar. Usage of pure moringa oleifera biodiesel in diesel engine under split injection strategy results in better combustion characteristics due to premixed and diffused heat release rate phasing with lower peak cylinder pressure. In addition, B100-10%-90% emits maximum nitric oxide emission of 1520 ppm, and least unburned hydrocarbon and carbon monoxide emission of 4 ppm and 0.01% vol respectively at 600 bar NOP with PIT of 35 °CA and MIT of 25 °CA. Moreover, Nitric oxide emission is reduced as the EGR rate gradually increases from 10% to 30%; on the other side, brake specific fuel consumption, carbon monoxide, and unburned hydrocarbon emissions are marginally increased. This research depicts that split injection strategy and EGR technique have simultaneously lowered the nitric oxide and smoke emissions while improving engine performance.