Dispersion and Explosion Characteristics of Hydrogen Released from a Hydrogen Fuel Cell Vehicle

Safety concerns regarding hydrogen dispersion, fire, and explosion hinder the commercialization of hydrogen fuel cell vehicles (HFCVs). This study developed and validated a numerical model for hydrogen leakage, dispersion, and explosion in representative accident scenarios using real-vehicle experimental data from a manufacturer-provided HFCV. The analysis examined the effects of leakage orifice diameter, leakage orientation, vehicle motion, and ignition timing on hazard evolution. Large-orifice leakage accelerates flammable cloud formation and expands the hazard range, whereas small-orifice leakage prolongs cloud persistence. Vehicle motion enhances turbulent mixing and reduces near-field accumulation. Immediate ignition produces a jet flame with a maximum radiative heat-flux impact distance of 44.1 m, whereas delayed ignition increases explosion severity and generates a peak overpressure of 0.14 bar. These findings support the risk assessment and safety design of HFCVs.