Effects of hydrogen addition on the explosion venting characteristics of hydrogen-propane-air mixtures

To study the effect of hydrogen fraction (n) in stoichiometric hydrogen-propane-air mixtures ranging from 0 to 1.0 on overpressure and external flame temperature, experiments on the vented explosion are conducted in a 1-m long cylindrical tube with a vent on the top surface. The explosion venting process is recorded by the high-speed shadowgraph imaging system, pressure testing system, and infrared thermal imager. The internal peak overpressure is proportional to the hydrogen fraction, and the external pressure peak (PExt) induced by the second explosion in the external flow field shows a similar trend. The higher external impulse occurs in higher hydrogen fractions and farther distances. The maximum flame length drops first and then rises with the addition of n. The maximum surface temperature of the external flame peaks at n = 1, followed by that of n = 0, n = 0.3, n = 0.9, and n = 0.6, respectively. Besides, the relative-safety radii, free of thermal radiant damage, are obtained. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.