Effect of N₂ and CO₂ on the Explosion Properties of High Equivalence Ratios of Hydrogen

Abstract

The explosion characteristics of premixed gases under different equivalence ratios (1.0–3.0) and inert gas addition (5–20%) are experimentally investigated, and sensitivity analysis of the radical reactions is carried out using the USC Mech II model to analyze the molar fraction of radicals. The results show that at high equivalence ratios, inert gas has little effect on flame stability. The addition of an inert gas reduces the tensile rate in the early stage of flame growth. At high equivalence ratios, CO 2 inhibits explosive flame propagation twice as effectively as N 2 . Due to the large heat capacity and chemical kinetic effects, CO 2 has a stronger inhibitory effect on the explosion pressure than N 2 , and the inhibition efficiency on the explosion strength is nearly twice that high. To further analyze the effect of different inert gas addition ratios on chemical kinetics, sensitivity analysis, and molar fraction simulations were performed. The thermal and chemical kinetic effects of CO 2 cause later generation of H and OH radicals and the partial chain reaction involving CO 2 causes a lower peak of H radicals than the peak of H radicals generated under an N 2 atmosphere. However, CO 2 is a direct reactant and the third body to produce a small chemical kinetic effect.