Effect of water content of hydrous ethanol on chemical kinetic characteristics based on the new developed reduced ethanol-toluene reference fuels mechanism

As a renewable energy, ethanol has attacked increasingly attention for spark-ignition engines due to its characteristics of high octane number and valuable oxygen content (34.74% v/v). However, little research expounds the fundamental of ethanol-gasoline blends in SI engines because of its complicated and changeable chemical kinetics mechanism. In this investigation, a reduced chemical kinetic model is proposed for the oxidation mechanism of ethanol-toluene reference fuels (TRF) blending fuels using the method of semi-decoupling methodology. The small molecule (H2 / CO / C1) mechanism is taken as the kernel in this model, and integrated the skeleton mechanism of ethanol into the TRF mechanism of gasoline surrogate as well, called E-TRF model, which contains 64 species and 194 elementary reactions. The simulated results of ignition delay times, laminar burning velocity, and in-cylinder pressure and heat release rate have been verified with the experimental data available in other literature under different operation conditions, respectively. The result shows that the ETRF model could accurately predict the combustion characteristics of the ethanol-gasoline fuel. In addition, the water content effects on the combustion of ethanol has been also analyzed. It is found that an increase of water content leads to a decline of the critical radical production and burning temperature, which suppresses the combustion progress and eventually results in a decrease of laminar burning velocity. Moreover, the physical effect of water is more than 90% on laminar burning velocity and the physical effect of water at different temperatures is more than 80% on ignition delay times.

Automated summary

The study proposed a simplified chemical kinetic model for the oxidation mechanism of ethanol-gasoline blended fuels and verified the combustion characteristics. The effects of water content on ethanol combustion were also analyzed in the research.