A Numerical Study on the Effects of Exhaust Gas Recirculation Temperature on Controlling Combustion and Emissions of a Diesel Engine running on HCCI Combustion Mode

In this study a comprehensive study is carried out numerically on a single cylinder four-stroke Diesel engine operating in homogenous charge compression ignition (HCCI) mode of combustion for the effects of exhaust gas recirculation (EGR) temperature and percentage on the combustion and emission characteristics. An advanced version of ANSYS IC Engine FORTE coupled with highly efficient and detailed pre-defined industry standard chemical kinetics CHEMKIN is used to solve the chemical reaction mechanism and species thermodynamic data. The analysis was carried out at three different EGR temperatures of 363K, 404K and 513K for 10%, 20% , 30%, 40% and 50% EGR each. The results predicted that the combustion ignition timing is advanced by increasing the EGR temperature. The effect of low EGR temperature is predominant at higher percentages of EGR. It was also found that the CO and UHC levels nearly kept constant with an increase in EGR temperature the NOx levels increase linearly with an increase in EGR temperature. The HCCI combustion in diesel engine can be controlled by adjusting the temperature and mass percentage of exhaust gas recirculation while retaining lower NOx emissions and very little increase in CO and unburnt hydrocarbons.