Numerical simulation of combustion and choosing the optimum model of multiple fuel injections on performance and emissions in D-87 diesel engine

The aim of this paper is studying performance parameters and pollutant emissions on D-87 diesel engine and simulation of multiple injections process and choosing the optimum pattern of its for simultaneous reduction of soot and NOx. The simulations are divided into two parts. In first part the effect of different ratio of fuel mass in each of the injection pulse is studied and in the second part the effect of pause period length between injection pulses on engine performance and emissions will be studied. The results show that, if the majority of fuel injected in the second pulse with the large dwell time between them, increased in-cylinder pressure and thus the engine brake power losses and eventually brake specific fuel consumption increases. Therefore, it is optimal that the majority of fuel injected at the first pulse. In the multiple fuel injection process, despite decreasing maximum combustion temperature because of increasing the fuel injection period, the soot pollutant is in safe range; therefore the basis for selecting optimal point is based on trade off between NOx and soot pollutants diagram, in addition will be considered based on the behavior curves compromise between performance and NOx.