Modeling of hydrogen dispersion and explosion of a fuel cell vehicle in an underground parking garage

Numerical simulations were conducted to investigate the hydrogen dispersion and deflagration in an underground garage, considering potential leaks from hydrogen fuel cell vehicles. This study constructed a geometric model based on vehicles equipped with 70 MPa hydrogen tanks and considered various accident scenarios by adjusting the orifice diameter and ignition time. The results indicated that the peak overpressure was influenced by the equivalence ratio, hydrogen distribution and ignition time. Specifically, increasing orifice diameter led to greater overpressure when ignition occurred 0.1 s after release, while the opposite trend was observed for ignition at 1 s or 10 s. Temperature and overpressure were measured to evaluate the hazard distances, revealing inconsistencies between distances determined by pressure and temperature, with the latter yielding larger results. This research contributes to determining affected areas and safety distances in hydrogen accidents, provides references for the design of parking intervals and the development of emergency plans.