Multidimensional modeling of the effect of EGR (exhaust gas recirculation) mass fraction on exergy terms in an indirect injection diesel engine

Abstract

In this investigation, the energy and exergy analyses are carried out for a Lister 8.1 IDI (indirect injection) diesel engine at four different EGR (exhaust gas recirculation) mass fractions (0%, 10%, 20% and 30%) and at 50% load operation. The energy analysis is performed during a closed cycle by using a three-dimensional CFD (Computational Fluid Dynamics) code. For the exergy analysis, an in-house computational code is developed, which uses the results of the energy analysis at different EGR mass fractions. The cylinder pressure results for baseline engine are compared with the corresponding experimental data that shows a good agreement. With crank position at different EGR mass fractions, various exergy components and the cumulative exergy are identified and calculated separately. It is found that at 50% load operation, as EGR mass fraction increases from 0% to 30% (in 10% increments), exergy efficiency decreases from 31.74% to 25.38%. Also, the cumulative irreversibility related to the combustion chamber decreases from 29.8% of the injected fuel exergy to 25.5%. This work demonstrates that multidimensional modeling can be used to simulate the effect of various EGR mass fractions and gain more insight into the impact of flow field on combustion process in IDI engines from the second law perspective.