Hydrogen Leakage Risks and Mitigation Measures in Large Underground Garages

Abstract Hydrogen fuel cell vehicles, characterized by zero emissions, pollution-free operation, and high efficiency, have emerged as a key focus in the development of the global automotive industry. The operating pressure for onboard hydrogen storage tanks commonly ranges from 30 to 70 MPa. Due to hydrogen's wide combustion and explosion concentration range and its exceptionally rapid combustion rate, there is a high risk of explosions and other accidents once equipment failure happens during storage and transportation. The research presented in this paper focuses on the analysis of hydrogen leakage from storage tanks in an underground garage using fluent simulations. The findings reveal that released hydrogen forms a jet from the storage tank under high pressure, dispersing along the ceiling upon reaching it and accumulating at the edges and corners. Moreover, larger leakage ports on the storage tank result in a greater mass flow of hydrogen, leading to an expanded diffusion range of the hydrogen cloud and decreased local concentration. To mitigate the risk of hydrogen combustion and explosion within the garage, this study introduces 16 extraction vents on the garage ceiling and six natural vents on its sides. The validation of the proposed hydrogen risk mitigation measures demonstrates their effectiveness in reducing the concentration and range of flammable clouds within the garage, especially when dealing with larger leakage ports.