Flame Temperature Correlation for the Effects of Exhaust Gas Recirculation on Diesel Particulate and NO _x Emissions

Effects of exhaust gas recirculation (EGR) on particulate carbon and NO_x emissions have been examined using a single-cylinder, divided-chamber diesel engine operating at several loads and speeds. For a fixed start-of-combustion timing, EGR reduced _x emissions while simultaneously increasing particulate carbon emissions. Results of this study indicate that the effects of EGR on both of these pollutants could be explained by variations in the stoichiometric flame temperature (Tf), which is the characteristic temperature of a diffusion-controlled combustion process. These results are consistent with an earlier study in which O₂ and N₂ were added to the intake air of a diesel engine.