Optimization of Exhaust Gas Recirculation System

Exhaust Gas Recirculation (EGR) is a method to control Nitrogen Oxide (NOx) emissions from automobile exhaust. In this method, small amount of the exhaust gas is recirculated into the combustion chamber through the air intake system. The exhaust gas is mixed with charge air just before entering intake manifold. Appropriate mixing of exhaust gas with charge air is necessary to ensure nearly equal amount of exhaust gas flow into all the cylinders. Present research efforts by various automobile manufacturers rely on commercial CFD simulation tools to identify and resolve flow and thermal issues occurring in various vehicle systems. The focus of this paper is to optimize the EGR system to obtain uniform distribution of recirculated exhaust gas to every cylinder of a six cylinder heavy duty diesel engine. CFD simulations were done for this engine using a commercial CFD solver. Mixing and transport of the two fluids was modeled using species transport approach. Appropriate geometric modifications were proposed based on simulation results.