Experimental study on the coupling effect of heptafluoropropane and obstacles with different slits on the methane-air explosion

The comprehensive effects of obstacles with different slit and heptafluoropropane on the methane-air explosion characteristics were studied by visual explosion experiment platform. The volume fraction of heptafluoropropane and the number of slits of obstacles were considered. The results show that in the absence of obstacles, 1% concentration of heptafluoropropane accelerates flame propagation. When the concentration of heptafluoropropane is 3%, the explosion overpressure increases by 24.2%, and when 5% heptafluoropropane is used, the overpressure decreases by 10.6%. With the addition of obstacles, the coupling effect of the inhibitor and the obstacle improves the inhibition effect of heptafluoropropane. For obstacles with 2, 3, and 4 slits, 1% concentration of heptafluoropropane failed to significantly accelerate the flame propagation process under obstacle conditions. When the concentration of heptafluoropropane is 3%, the explosion overpressure increases by 9.5%, 5.4%, and 7.5%, respectively. The overpressure decreased by 18.7%, 25.7%, and 20.6% when 5% heptafluoropropane is added. The coupling mechanism significantly enhances the suppression effect of heptafluoropropane on methane explosion under various obstacle conditions. •The coupling effect enhances the inhibitory effect of heptafluoropropane.•Heptafluoropropane does not accelerate flame propagation downstream of obstacles.•The suppression effect of heptafluoropropane on explosion overpressure is enhanced.•The coupling mechanism between obstacles and heptafluoropropane was analyzed.