Flameless venting characteristics of hydrogen explosion under the coupling of carbon dioxide and metal foam

Abstract

To avoid the hazards of vented flame and external explosion caused by hydrogen-air explosion venting, the effects of metal foam and carbon dioxide on the characteristics of vented flame, reduced overpressure, and external pressure are investigated. The results indicate that a combination of inerting (such as adding CO2) and venting technology is recommended to achieve the quenching of vented flames without increasing the reduced overpressure of hydrogen explosions. The effect of the thickness of metal foam and the concentration of CO2 on the length of vented flame is significant, but it only has a minor impact on the width. The laminar burning velocity of hydrogen decreases with the increase of the volume ratio of CO2, which weakened the chemical reaction and reduced overpressure and explosion severity (KG). The characteristics of the external explosion are revealed with the assistance of BOS images. When the venting diameter is 80 mm, the flameless venting efficiency is approximately at 53.33%. Finally, the criterion for heat transfer quenching of vented flames is discussed. The quenching mechanism during flameless venting of hydrogen explosions is analyzed, providing a basic reference for the safety design of hydrogen explosion protection.