Effect of inert gas injection parameters on explosion suppression of H2-CH4 mixtures

LI Shengli; WANG Changlu; ZHENG Yi; LI Bin

doi:10.13272/j.issn.1671-251x.2025060021

Abstract：To investigate the effect of inert gas injection parameters on the explosion characteristics of H2-CH4 mixtures,experiments were carried out in a horizontal pipeline to study the suppression of H2-CH4 mixture explosions by N2 and CO2.The effects of N2 and CO2 injection positions and injection angles on explosion pressure,flame propagation speed,and flame front temperature of H2-CH4 mixtures were examined.The results showed that N2 and CO2 significantly reduced explosion pressure,flame propagation speed,and flame front temperature,and that the suppression effect of CO2 on H2-CH4 mixture explosions was stronger than that of N2.The suppression ability of inert gas was better when injected at the near-flame end than at the far-flame end.As the injection angle of inert gas increased,the maximum explosion pressure,flame propagation speed,and flame front temperature gradually decreased,and the suppression effect on H2-CH4 mixtures gradually increased.Chemkin-Pro simulations indicated that,with the addition of CO2,the peak molar fractions of H radicals and OH radicals decreased by 14.2％and 9.9％,respectively,compared with the condition without suppression;whereas with the addition of N2,the molar fractions of H radicals and OH radicals were almost unchanged compared with the condition without suppression.The combined injection mode of"near-flame end+large angle"could maximize the synergistic suppression effect of CO2 in terms of radical consumption,physical heat absorption,and combustible gas dilution,while the combined injection mode of"far-flame end+small angle"weakened the suppression efficiency of inert gas due to the dual limitations of diffusion delay and gas mixing non-uniformity.