Methanol-gasoline Dual-fuel Spark Ignition (DFSI) combustion with dual-injection for engine particle number (PN) reduction and fuel economy improvement

To meet the near future emissions legislations of SI (spark ignition) internal combustion engines, this paper presents an experimental study on the M-G DFSI (Methanol-Gasoline Dual-fuel Spark Ignition) combustion for reducing PN (particle number) emissions and improving fuel economy in a high compression ratio gasoline engine. M-G DFSI was operated using port-injection of a highly oxygenated, high latent heat and high octane number fuel to reduce PN emissions and improve fuel economy, direct injection of a high energy density and high volatility fuel to obtain fast load response and high load. The effects of the ratio of methanol to gasoline during DFSI at stoichiometric conditions on PN reduction and fuel economy improvement were investigated. As the proportion of PFI-Methanol increases, the absolute and relative BSFCequivalent improvement in terms of fuel economy will be extended almost linearly. Also, both the nucleation mode and accumulation mode of PN emissions drops dramatically. Furthermore, there is an optimal PFI-methanol mass fraction value to get sufficient fuel economy improvement and PN emissions reduction while reaching the peak performance. It can be shown that Methanol-Gasoline DFSI is a potential combustion strategy to reduce PN emissions effectively and significantly improve fuel economy in practical applications of gasoline engines. (C) 2015 Elsevier Ltd. All rights reserved.