Effects and kinetic mechanisms of suppression gases on H2/air mixture explosions: A comparative study

Abstract

This study systematically investigated the effects of various inhibitors (N₂, CO₂, Ar, and C₃HF₇) and two composite inhibitors on hydrogen explosions at identical equivalence ratios to elucidate their suppression mechanisms. Numerical simulations revealed the kinetic characteristics of hydrogen explosion processes under inhibitor effects. The results demonstrate that explosion intensity progressively decreases with increasing inhibitor concentration. While N₂, CO₂, and Ar suppress explosions through both dilution and endothermic effects, CO₂ additionally exhibits chemical inhibition via radical consumption. At low concentrations, CO₂ shows weaker suppression than N₂ and Ar due to limited chemical inhibition, but its effectiveness significantly improves at higher concentrations. Although low-concentration C₃HF₇ promotes explosion pressure through thermal effects, higher concentrations enable comparable suppression efficiency as its pyrolyzed fluorinated products consume critical radicals (H·, O·, and OH·). The C₃HF₇CO₂ composite system effectively counteracts the pressure-enhancing effect of low-concentration C₃HF₇. Through synergistic physical and chemical inhibition, it suppresses key radical generation, reduces radical concentration and heat release rate, while enhancing OH radical and temperature sensitivity, thereby achieving efficient explosion suppression at low inhibitor concentrations. These findings provide theoretical support for hydrogen energy safety, risk management, and the development of composite suppressants.