The influence of methane blending ratio on the spontaneous combustion characteristics of high-pressure hydrogen leakage

¹ School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, Shaanxi, China
² Shaanxi Engineering Research Center for Industrial Process Safety and Emergency Rescue, Xi’an 710054, Shaanxi, China
³ Shaanxi Key Laboratory of Prevention and Control of Coal Fire, Xi’an 710054, Shaanxi, China

^* Corresponding author’s email: 1054713550@qq.com

Abstract

Adding CH₄ to high-pressure H₂ is considered one of the effective and convenient measures to reduce high-pressure H₂ leakage and spontaneous combustion, which is conducive to improving the safety of H2 energy storage. Based on the independently built high-pressure hydrogen leakage and self ignition experimental platform, the influence of CH₄ on the critical self ignition pressure and flame of high-pressure H2 leakage and self ignition was tested. The results indicate that the addition of methane can effectively increase the critical spontaneous combustion pressure. When 20% CH₄ is added, the critical self ignition pressure can be increased by 151.58%. Under similar discharge pressure conditions, the flame velocity in the pipeline decreases from 1224.64m/s for pure H₂ to 1024.07m/s for 10% CH₄. In addition, after mixing CH₄, the dispersion time of the jet flame is advanced, the flame duration is shortened, and the flame brightness is reduced. There are two main reasons for the mixed inhibition of spontaneous combustion by CH₄. On the one hand, it reduces the Mach number of shock wave propagation, thereby lowering the ignition temperature. On the other hand, the activity of the fuel system decreases, and the heat required for self ignition increases.