Investigation on the effect of injection timing on Exergy Terms in an RCCI engine

The purpose of this study is to investigate the effect of injection timing on various exergy terms of reactivity control combustion ignition with natural gas fuels and n-heptane, which are considered low and high fuel reactivity, respectively. The engine is simulated using a three-dimensional model and the numerical results are compared with the experimental data and the accuracy of model is validated. Thermomechanical exergy, chemical exergy, work, exergy of heat transfer and the amount of irreversibility are calculated in each times step. The results show that fuel burns more perfectly by advanced start of injection due to more fuel and air mixing time. This causes the in cylinder temperature charge to be high enough to increase the heat transfer exergy due to increased heat transfer. In addition, the high temperature in the case when the start of injection is too advanced leads to an increase in irreversibility due to an increase in the number of chemical reactions.