To alleviate the shortage of petroleum resources and the air pollution caused by the burning of fossil fuels, the development of renewable fuels has attracted widespread attention. Among the various renewable fuels, ethanol can be produced from biomass and does not require much modification when applied to practical engines, so it has been widely used. However, ethanol fuel has a higher heat of vaporization than gasoline, it is difficult to evaporate and atomize under cold start conditions. Besides, the catalyst has not reached the conversion temperature at this time, resulting in lower conversion efficiency. These factors all lead to higher pollutant emission levels in ethanol-gasoline blends.
To solve the above problems, this research used visualization techniques to compare the effects of flash boiling and high-energy ignition technologies on the in-cylinder combustion process and pollutant emission of ethanol-gasoline blends fuel. Research results show that heating the fuel to 90 °C to achieve flash boiling can promote the atomization, evaporation, and mixture preparation of the spray so that a faster flame speed and lower cycle-to-cycle variations were generated. IMEPN has been increased from 1.80 bar to 2.10 bar, an improvement of approximately 16.6%, and the maximum fuel consumption can be reduced by 6.37%.
With the help of a high-energy ignition system, the formation of the initial flame kernel can be promoted, and the stability of earlier flame propagation can be improved, IMEPN has been increased from 1.80 bar to 2.18 bar, and the maximum emission of particulate matter can be reduced by 23.7%. Finally, this study has conducted in-depth research on the combustion process and pollutant generation of ethanol-gasoline under cold start conditions and proposed effective suppression strategies to maximize the energy-saving and emission-reduction potential brought by the addition of ethanol.