Thermal suppression effects of diluent gas on the deflagration behavior of H2–air mixtures

In this paper, the effects of diluted gas (N2, CO2) on the pressure and time parameters of hydrogen explosion are tested by experiments. The combustion heat loss and thermodynamic state parameters during combustion were also calculated. The results show that as the diluent gas content increases, the maximum hydrogen explosion pressure decreases, and the rapid hydrogen deflagration time increases. The effect of dilution gas on hydrogen explosion pressure parameters and explosion time parameters in the rich-combustion state is more significant than that in the lean-combustion state. When φ = 1.0 and 20% of N2 and CO2 are added, the heat loss per unit area increases approximately 3.23 times and 4.97 times, respectively. The thermal diffusivity did not change as the N2 content increased under different equivalence ratios but decreased linearly as the CO2 content increased. When the CO2 content increases from 5% to 30% at φ = 0.6, α decreases by 14.1%. N2 has no significant effect on the adiabatic flame temperature under the lean-combustion state. At different equivalence ratios, the adiabatic flame temperature decreases linearly as the CO2 content increases, and the inhibition effect of CO2 on the adiabatic flame temperature is significantly higher than that of N2.