Understanding the mechanisms of flame quenching and flame-wall interactions in microchannel

Abstract

The flow resistance and quenching characteristics of hydrogen flame in the microchannel of corrugated plates under a nitrogen environment are investigated in this paper. The analysis reveals that the explosion pressure and flame velocity decrease as the aperture of the microchannel decreases. Adding 24 % nitrogen increased the hydrogen quenching diameter from 0.5 mm to 1.4 mm in the case of the stoichiometric ratio. In light of the impact of nitrogen and microchannel characteristics, a critical flame velocity prediction formula for hydrogen flames has been established. To clarify the flame quenching mechanism, kinetic simulations and heat transfer calculations are conducted. The flow resistance and quenching temperature under different microchannel diameters are obtained. As the microchannel aperture decreases and the nitrogen concentration increases, the quenching temperature of hydrogen rises. Combined with the exothermic reaction and the heat transfer of microchannel, the flame-wall heat transfer in the microchannel is analyzed in detail. A reduction in the diameter of microchannels is beneficial in terms of enhancing the flame-wall interaction, and promote the thermal and free radical quenching of hydrogen flame. The results can be employed to elucidate the mechanism of hydrogen flame quenching and to reduce the thermal runaway hazard of hydrogen.