Laminar Combustion Characteristics of Ethanol-Hydrogen Premixed Fuel

[Objective] With the depletion of fossil fuels and bio-fuels' emergence, ethanol-hydrogen hybrid fuel as a new generation of renewable clean fuel has attracted wide attention, so it is necessary to study the effect of ethanol-hydrogen premixed flame combustion characteristics. [Method] Based on the constant volume combustion system and combined with high-speed schlieren technology, the effects of the equivalent ratio and pressure on the laminar combustion characteristics of ethanol-hydrogen premixed flame were studied under the conditions of initial temperature of 370 K, hydrogen ratio of 50%, equivalent ratio of 0.7~1.4 and initial pressure of 1, 2 and 4 bar. Focusing on the propagation combustion characteristics of the flame, the laminar combustion velocity was calculated and its influencing factors were analyzed. The relevant reaction model was established with the help of Chemkin simulation platform, and the chemical dynamics of the laminar combustion characteristics were analyzed in detail by using Marinov's ethanol oxidation reaction mechanism. [Result] The results showed that the laminar combustion velocity was positively correlated with the adiabatic flame temperature and reached the maximum value around φ=1.1. The pressure significantly affects the net heat release rate, and the peak value occurs in the higher temperature region with a greater equivalent ratio. R1:H+O2⇔O+OH represents the most sensitive reaction which promotes the laminar combustion velocity of the flame. With the increase of pressure, the peak molar fraction of H, OH, and O free radicals gradually decreased and moved upstream. With the increase of the equivalent ratio, the molar fraction of H and O free radicals gradually decreased, and the molar fraction of OH free radicals first increased and then decreased. [Conclusion] The equivalent ratio, pressure and active free radicals have significant effects on the laminar combustion characteristics of ethanol-hydrogen premixed fuel, which can provide theoretical basis for subsequent studies.