The influence of exhaust gas recirculation coupling with fuel injection pressure on the combustion and emission characteristics of engine fueled with methanol-gasoline blends

This study investigates the influence of EGR (exhaust gas recirculation) coupled with injection pressure on the combustion and emission characteristics of an engine fueled with methanol-gasoline blends. Increasing the methanol blending ratio can improve the knocking phenomenon, BTE (brake thermal efficiency) and regulated emissions. As the methanol blending ratio increases, the optimal fuel injection pressure for achieving the optimal combustion process, BTE and CO (carbon monoxide) emissions increases. The optimal EGR rate for achieving the highest BTE also increases. As the methanol blending ratio increases, the optimal injection pressure for achieving the lowest TPN (total particle number) and NPN (nucleation mode particle number) also increases. Increasing the fuel injection pressure leads to a decrease in APN (accumulation mode particle number). Increasing the methanol blending ratio and EGR rate can reduce TPN and NPN. With increasing methanol blending ratio, APN initially increases and then decreases. When using a lower methanol blending ratio, increasing the EGR rate leads to a higher proportion of APN to TPN. However, when using a higher methanol blending ratio, the opposite is true. The optimal engine performance can be achieved by using M100 fuel with a 35 MPa injection pressure and a 30% EGR rate.