Effects of HPL and LPL EGR Gas Mixed Supply on Combustion and Emissions in Automotive Diesel Engine

This paper has investigated the effects of High Pressure Loop (HPL) and Low Pressure Loop (LPL) Exhaust Gas Recirculation (EGR) gas mixture on combustion and emissions characteristics in a light-duty automotive diesel engine. This mixed supply strategy of dual-loop EGR is expected to be efficient for the reduction of NO_xand smoke without the loss of turbocharger power. The results from the combined HPL and LPL EGR system were compared with those from only HPL EGR and only LPL EGR system respectively. Characteristics including temperature and mass flow rates of intake charge, air excess ratio, O₂ concentration in intake charge, difference in pressure between intake and exhaust, pumping loss, fuel consumption, CO, HC, NO_x emissions, and smoke opacity were compared and analyzed at two operating conditions. Fuel consumption, NO_x emission, and smoke were reduced with dual EGR mixture. However, CO and HC emission was little bit increased as a portion of LPL EGR increased at the same total EGR rate.