Experimental investigation on the effect of vent film material and thickness and hydrogen fraction on explosion-venting features of H2/CO/Air mixtures within a horizontal duct

To gain insights into the explosion-venting properties of hydrocarbon fuels and mitigate explosion risks, the explosion parameters of H2/CO/Air within a duct equipped with a lateral vent were experimentally investigated. The coupling effects of three common vent films (0.01 mm-thickness polyethylene (PE), 0.025 mm-thickness polyethylene terephthalate (PET0.025) and 0.05 mm-thickness polyethylene terephthalate (PET0.05)) and four hydrogen fractions (φ = 10%, 30%, 50% and 70%) on explosion characteristics were determined. The results revealed that the flame propagation velocity exhibited four modes dependent on vent film and hydrogen fraction. Given the same vent film, the flame velocity variation mode was similar for different hydrogen fractions. The presence of a lateral vent did not always inhibit the flame propagation. For the PE case, the lateral vent had a significant impact on the flame propagation. While for the PET0.025 and PET0.05 cases the flame propagation was primarily influenced by the end vent. Both the flame front structure and the explosion overpressure under different conditions were analyzed. The effect of vent film material and thickness was more significant than hydrogen fraction with respect to the flame shape, flame propagation velocity, and explosion overpressure.