Effects of reformed exhaust gas recirculation (REGR) of ethanol-gasoline fuel blends on the combustion and emissions of gasoline direct injection (GDI) engine

Transportation is one of fast-growing sources of greenhouse gas emission worldwide. Road transport accounts as the main cause of HC, CO, NOX, CO2, and PM emissions. Ethanol blended fuel could improve engine performance and reduce both gaseous and PM emissions. Meanwhile, reformed exhaust gas recirculation (REGR) is introduced to achieve simultaneous reduction of NOX and PM from gasoline engines. In this work, the effect of REGR on combustion characteristics, and emissions of the gasoline direct injection (GDI) engine fuelled with ethanol-gasoline fuel blends (E10 and E20) was investigated. The H2 and CO mixture were used as a simulated REGR charge which was fed to the GDI engine's intake manifold. The H2/CO ratio was determined via modelling of ethanol-gasoline fuel blend reforming based on equilibrium analysis. Moreover, the characteristics of PM emission (e.g. size distribution, primary particle size, morphology) were explored using TEM imaging. The results revealed that REGR could simultaneously improve both the engine thermal efficiency and engine-out emissions. A total number of PM particles and average primary particle size were reduced and compared with baseline (no-EGR) condition. An insight from this investigation can be used for designing control strategies to reduce the negative impact of internal combustion engine usage on human health and environment.