Study on the influence of multicomponent gases on the dynamic characteristics of gas explosion
The influence of the multi-component mixed gas,with a composition and ratio of V(C2 H6)∶V(C2 H4)∶V(CO)∶V(H2)=5∶5∶1∶1,on the explosion characteristics of 7％,9.5％,and 11％volume fraction of CH4 was investigated using a 20 L spherical explosive device.Additionally,the CHEMKIN software was used to simulate the changes of H·,O·,and·OH in the explosion reaction of mixed gas with different ratios,as well as the sensitivity of elementary reactions.The relationship between the maximum explosion pressure and the peaks of the molar fraction of H·,O·,and·OH was analyzed.The results indicate that when adding the multi-component mixed gas to CH4 with a volume fraction of 7％,the maximum explosion pressure and the maximum rate of pressure rise increase,and the time to reach the maximum explosion pressure is delayed.However,when the volume fraction of CH4 reaches 9.5％or 11％,the opposite effect is observed.For CH4 with a volume fraction of 7％,the addition of the multi-component mixed gas increases the peaks of the molar fraction of H·and·OH and shortens the time to reach the peak.When the volume fraction of CH4 is 9.5％or 11％,the peak of the molar fraction of H·increases,while the peaks of the molar fraction of O·and·OH decrease.Besides,there is a linear relationship between maximum explosion pressure and the peaks of the molar fraction of H·,O·and·OH.Usually,the peaks of the molar fraction of H·,·OH,and maximum explosion pressure vary in the same trend,while the linear relationship between maximum explosion pressure and O·is bounded by an equivalence ratio of 1.When the equivalence ratio is less than 1,the higher the peak of the molar fraction of O·,the lower the maximum explosion pressure.Conversely,when the equivalence ratio is greater than 1,the trend is reversed.Furthermore,the correlation between maximum explosion pressure and the peaks of the molar fraction of free radicals decreases as the equivalence ratio increases.The sensitivity analysis indicates that R38(H+O2⇔O+OH)is the main oxygen-consuming reaction,consuming one mole of H·and producing one mole of O·and one mole of·OH,thereby increasing the destruction rate of CH4.Consequently,it is one of the fundamental reactions to control the CH4 consumption rate and the release of explosion reaction energy.Therefore,when there is less O2,the R38 reaction is constrained,macroscopically resulting in a weaker explosion effect at a high equivalence ratio.
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