Investigation on explosion characteristics of hydrogen-air mixtures diluted with inert gases in confined spaces

Hydrogen energy is essential for improving environmental issues and developing sustainability. It is important to investigate the kinetic mechanism of hydrogen explosion suppression to clarify the prevention and control of hydrogen explosion disasters. A 20L spherical explosion test equipment is used to conduct suppression experiments of hydrogen-air mixture explosions with various inert gases. The evolution of flame behaviour and explosion pressure in the container is recorded, respectively. The microscopic suppression mechanism of different inert gases in the H2-air premixed gas explosion is revealed by comparing the inhibition effects and analyzing the macroscopic physical parameters characteristics of the hydrogen explosion under a diluted environment. The findings indicate that the hydrogen explosion reaction rate reduces as the concentration of inert gas increases and that the flame propagation radius, maximum explosion pressure, and maximum pressure rise rate all drop linearly. The same proportion of gas diluent has different suppression effects on H2 explosion. CO2/N2 not only mitigates hydrogen explosion at the physical level but also affects the changes of free radicals through chemical competition. CO2 has the most significant restriction on various explosion characteristic parameters and flame propagation, followed by He and N2. The research results support the safe application of hydrogen energy.