This study employed FLACS software to simulate hydrogen leakage scenarios involving a Toyota Mirai Gen II fuel cell vehicle in underground parking garages, to systematically investigate the impacts of ventilation scheme, vent orientation, and ventilation rate. Results indicate that the combined action of the suspended ceiling and ventilation system completely removes the flammable gas clouds, achieving the highest hydrogen removal efficiency. Upward-exhaust ventilation is more effective than other orientations. At a ventilation rate of 24 air changes per hour （ACH）, the peak equivalent stoichiometric cloud volume is 22.5% lower than that for no ventilation, and the cloud removal time is 43.4% shorter than that at 12 ACH. Further increases in ventilation rate provide limited enhancement in flammable cloud evacuation efficiency.

hydrogen  /  ventilation  /  numerical simulation  /  underground parking garage  /  hydrogen fuel cell vehicle  /  leakage and dispersion