Experimental study on the effect of high-pressure and low-pressure exhaust gas recirculation on gasoline engine and turbocharger

Xianqing Shen,Zhendong Zhang,Kai Shen

doi:10.1177/1687814018809607

Abstract

The effects of high-pressure and low-pressure exhaust gas recirculation on engine and turbocharger performance were investigated in a turbocharged gasoline direct injection engine. Some performances, such as engine combustion, fuel consumption, intake and exhaust, and turbocharger operating conditions, were compared at wide open throttle and partial load with the high-pressure and low-pressure exhaust gas recirculation systems. The reasons for these changes are analyzed. The results showed EGR system of gasoline engine could optimize the cylinder combustion, reduce pumping mean effective pressure and lower fuel consumption. Low-pressure exhaust gas recirculation system has higher thermal efficiency than high-pressure exhaust gas recirculation, especially on partial load condition. The main reasons are as follows: more exhaust energy is used by the turbocharger with low-pressure exhaust gas recirculation system, and the lower exhaust gas temperature of engine would optimize the combustion in cylinder.

Highlights

With the fuel consumption and emission regulations becoming more stringent, exhaust gas recirculation (EGR) technology has been used in the gasoline engine to reduce NOx and particulate emissions.[14,15]
It is found that EGR can reduce the fuel consumption of gasoline engine.[16,17]
At partial load, there are some reasons for better fuel consumption better with LP EGR: (1) compared with the HP EGR system, the exhaust gas passes through the turbine and the booster intercooler, which makes the intake temperature lower

Summary

Introduction

With the energy crisis and environmental problems becoming increasingly serious, engines with lower fuel consumption and lower exhaust emissions have become a trend.[1,2] Small-displacement and small-size turbocharged gasoline direct injection (GDI) engine[3,4,5,6,7] has attracted wide attention in lowering engine fuel consumption, improving thermal efficiency and reducing emissions.[1,8,9]engine miniaturization and high turbocharged pressure lead to the high load, which will increase the knocking tendency of the engine.[10,11] The conventional solutions, such as delaying the ignition advance angle or decreasing the compression ratio, will sacrifice the thermal efficiency of the engine.[12,13]In recent years, with the fuel consumption and emission regulations becoming more stringent, exhaust gas recirculation (EGR) technology has been used in the gasoline engine to reduce NOx and particulate emissions.[14,15] It is found that EGR can reduce the fuel consumption of gasoline engine.[16,17]. At low speed and high load, the HP EGR cannot be stably introduced, owing to the too small pressure difference between the intake and exhaust.

Results

Conclusion