Abstrait

NUMERICAL INVESTIGATION OF EFFECT OF EXHAUST GAS RECIRCULATION ON COMPRESSIONIGNITION ENGINE EMISSIONS

Aman Kumar Jha, Ashwini Pavgi, Rajavi Yeolekar

In today’s technological world, it is difficult to neglect the extensive usage of IC engines. Though diesel engines are preferred over gasoline engines because of various reasons, they produce higher emissions particularly oxides of nitrogen (NOx) and soot. Attempts are made to design an engine with better efficiency and minimum emissions by modifying the existing engine technologies and developing better after treatment systems. Since after-treatment systems are costly and occupy more space, in-cylinder solutions like exhaust gas recirculation (EGR), variable compression ratio, air intake improvements, and fuel injection characteristics are preferred. CONVERGE, a computational fluid dynamics (CFD) tool, is used for this analysis. Adaptive Mesh Refinement (AMR), parallelization and other powerful capabilities of CONVERGE have made it most suitable for engine studies. Numerical pressure curve has been validated against the generated experimental data. A very good comparability has been observed for the pressure curve over a wide range of crank angle. Based on good validation, Converge tool is used to study the effects of EGR on diesel engine emissions. The results indicate that the use of EGR leads to a decrease in peak pressure, which in turn reduces NOx. At the same time, there is an increase in soot amount. HC and CO emissions were also increased with increasing amount of EGR. The presence of CO2 and H2O in EGR increase the delay and reduce the reaction rate.