Influence of Low Pressure Exhaust Gas Recirculation on Combustion and Fuel Consumption of Turbocharged Direct Injection Gasoline Engine

Abstract:

A turbocharged direct injection miller cycle engine was selected and a low pressure exhaust gas recirculation (LP-EGR) was installed. By changing the EGR rate, the influence of LP-EGR on the combustion and fuel consumption of gasoline engine was studied. The results show that: under medium and small load conditions, fuel consumption reduces with the decreasing of pumping loss by changing the EGR rate, and the fuel consumption can be reduced by up to 8.41%. Under heavy load conditions, fuel consumption reduces with the EGR by inhibiting knock and modifying ignition time, and the fuel consumption can be reduced by up to 5.67%. Under near full load conditions, fuel consumption reduces by lowering exhaust temperature and “over injection”, and fuel consumption can be reduced by 20.4%. With the EGR, combustion will slow down and coefficient of variation will increase. With the increasing of EGR rate, the ignition time delays and the combustion duration increases, but the maximum heat release rate and the maximum temperature in the cylinder decrease. Because of optimized ignition advance angle, the maximum pressure in cylinder increases.