Abstract: Gas/coal dust mixed explosion is a complex phenomenon of homogeneous-heterogeneous coupled combustion, and its dominant combustion mechanism dynamically evolves. Compared with single component explosion, it has higher explosion intensity and constitutes an important challenge in coal mine disaster prevention and control. Based on a 20 L spherical explosion testing device, this article investigates the inhibitory effects of two inert gases (N2 and CO2) on CH4/coal dust composite explosions. By comparing the changes in explosion characteristic parameters under different gas concentration conditions, the differences in explosion suppression efficiency between the two inert gases and their mechanisms of action are revealed. The research results indicate that N2 and CO2 have inhibitory effects on CH4/coal dust composite explosions under different composite conditions, with CO2 showing a significantly better explosion inhibition effect than N2. In the explosion inhibition process, both CO2 and N2 have exerted dilution and cooling effect. CO2 consumes the key active free radical H· generated during the explosion process through elementary reactions, thereby reducing the content of active free radicals in the explosion reaction system and effectively delaying the explosion reaction rate. The research results can provide theoretical basis and quantitative reference for the prevention and control of coal mine explosion disasters.

Key words: CH4, coal dust, composite explosion, carbon dioxide, nitrogen, explosion inhibition