Effect of Hydrous Ethanol Combined with EGR on Performance of GDI Engine 2020-01-0348

In recent years, particulate matters (PM) emissions from gasoline direct injection (GDI) engines have been gradually paid attention to, and the hydrous ethanol has a high oxygen content and a fast burning rate, which can effectively improve the combustion environment. In addition, Exhaust gas recirculation (EGR) can effectively reduce engine NOx emissions, and combining EGR technology with GDI engines is becoming a new research direction. In this study, the effects of hydrous ethanol gasoline blends on the combustion and emission characteristics of GDI engines are analyzed through bench test. The results show that the increase of the proportion of hydrous ethanol can accelerate the burning rate, shorten the combustion duration by 7°crank angle (CA), advance the peak moment of in-cylinder pressure and rate of heat release (RoHR) and improve the combustion efficiency. The hydrous ethanol gasoline blends can effectively improve the gaseous and PM emissions of the GDI engine. Among them, the concentrations of carbon monoxide (CO) and hydrocarbon (HC) decrease by 10.6% and 12.2%, the concentration of PM drops by three orders of magnitude, and the particle size of the particles is transferred from the accumulation state to the nuclear state. Furthermore, a GT-Power one-dimensional simulation model is established to study the dual effects of EGR technology combined with hydrous ethanol gasoline blends. The results show that the fuel economy is improved under partial load due to the introduction of EGR. The emission results show that the combination of hydrous ethanol gasoline blends and EGR can improve combustion environment, which makes nitrogen oxides (NOx) emission reduce by 85.7%.