Comparative study on alcohols–gasoline and gasoline–alcohols dual-fuel spark ignition (DFSI) combustion for high load extension and high fuel efficiency

This paper presents an experimental study of the alcohols–gasoline and gasoline–alcohols dual-fuel spark ignition (DFSI) combustion for knock suppression and higher engine efficiency using a gasoline engine with high compression ratio. Alcohols–gasoline DFSI is organized using a port fuel injection (PFI) of high oxygenated, high latent heat of vaporization, and high octane alcohol fuel to suppress knock and a direct injection (DI) of high energy density and high volatility fuel to extend engine load, while gasoline–alcohols DFSI is organized by gasoline PFI and alcohol DI. Three different alcohols were studied, including methanol, ethanol, and hydro-ethanol. The engine was naturally aspirated and operated at stoichiometric condition. In each test, the percentage of alcohol injection was varied from 0 to 100%. The effects of these two combustion modes on knock-limit extension, fuel economy, and combustion characteristics were investigated. Both alcohols–gasoline DFSI and gasoline–alcohols DFSI are promising approaches of using alternative alcohol fuels in practical gasoline engines with significant improvement in engine efficiency and knock suppression. Gasoline–alcohols DFSI exhibits better anti-knock performance and achieves higher fuel efficiency than alcohols–gasoline DFSI.