Evaluation of unrestricted hydrogen and hydrogen-methane explosion venting through duct

This work is aimed at evaluating unrestricted duct-vented explosion of hydrogen-air mixture and hydrogen-methane-air mixture. The flame behavior in the venting zone and explosion pressure inside explosion chamber are obtained in the experiments. On the assumption of only fresh mixture venting or only combustion product venting, a mathematical model of unrestricted duct-vented explosion is established by considering chocked venting. The results indicated that the chocked venting could be achieved for unrestricted hydrogen and hydrogen-methane explosion venting due to the fact that the Mach disc structure is appeared in venting zone. Maximum explosion pressure and maximum pressure rise rate could be reduced significantly by unrestricted duct-venting. For the unrestricted hydrogen explosion venting, maximum explosion pressure and maximum pressure rise rate increases until phi = 1.5, then decreases monotonously with the increase of equivalence ratio. For the unrestricted hydrogen-methane explosion, maximum explosion pressure and maximum pressure rise rate continue to decrease with the increase of methane addition. Maximum explosion pressure in the experiment is between theoretical values of fresh mixture venting and combustion product venting. Maximum explosion pressure and pressure rise rate are increased with increasing burning velocity whether it is fresh mixture venting or combustion product venting. Maximum explosion pressure is increased linearly with increasing nondimensional vent coefficient. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.