Experimental Study of the Suppression Effect of N2/CO2 On the LPG Explosion Behavior in a Half-Open Duct with Large Aspect Ratios.

This work aims to investigate the effect of N₂/CO₂ on the explosion behavior of premixed liquefied petroleum gas (LPG)-air in a half-open duct. Experiments were performed in a duct (L/D = 47.5) with the ignition end closed and the other end open. Firstly, the optimal explosion concentration of LPG was determined using the stepwise approximation method, secondly, the effects of different volume fractions (VFs) of N₂/CO₂ on the pressure dynamic process, flame propagation velocity, and explosion severity of LPG-air explosion were analyzed, and finally the inerting effects of N₂ and CO₂ were compared using the control variable method. The results show that the explosion pressure and flame propagation velocity reach a maximum when the VF of LPG is 4.8% (without inert gas), and two pressure peaks (the first pressure peak (P₁) and the second pressure peak (P₂)) are observed. When the VF of LPG is 4.8%, the maximum pressure and the average flame propagation velocity in the tube decrease and the explosion intensity inside and outside the duct was effectively mitigated as the VF of N₂/CO₂ increases, and the explosion is completely suppressed as the VF of inert gas reached 30%. P₂ is significantly suppressed, and the maximum explosion pressure (P_max) occurs at $${P_1}$$ P 1 when the VF of N₂/CO₂ is above 15%. The suppression effects of CO₂ are more remarkable at a lower VF (below 18%), those of N₂ are more significant at a higher VF (above 18%), and P₁ also follows this rule. For a given volume fraction of inert gas, the suppression effect of N₂/CO₂ on the degree of explosion severity becomes more significant when approaching the optimal LPG explosion concentration (4.8%). [ABSTRACT FROM AUTHOR]