The rise in hydrogen fuel cell electric vehicles (FCEVs) is expected to pose a variety of hazards on the road. Vehicles using hydrogen could cause significant damage, owing to hydrogen vapor cloud explosions, jet fires caused by leakage, or hydrogen tank explosions. This risk is expected to further increase in semi-enclosed spaces, such as underground parking lots and road tunnels. Therefore, it is necessary to study the fire safety of hydrogen vehicles in semi-enclosed spaces. In this study, an experiment on hydrogen tank explosion was performed. In addition, the CFD numerical model was verified using the experimental results, and the damaging effect due to pressure propagation during hydrogen tank explosions in underground parking lots and road tunnels was analyzed using numerical analysis. From the experiment results, the hydrogen tank exploded at about 80 Mpa, a maximum incident pressure is generated 267 kPa at a distance of 1.9 m. As a result of numerical analysis based on the experimental results, the limit distance that can cause serious injury due to the explosion of a hydrogen tank in a road tunnel or underground parking lot was analyzed up to about 20 m from the point of explosion.

With an increase in the use of eco-friendly vehicles such as hybrid, electric, and hydrogen vehicles in response to the global climate crisis, accidents related to these vehicles have also increased. Numerical analysis was performed to optimize the safety of first responders responding to hydrogen vehicle accidents wherein hydrogen jet flames occur. The influence range of the jet flame generated through a 1.8-mm-diameter nozzle was analyzed based on five discharge angles (90, 75, 60, 45, and 30°) between the road surface and the downward vertical. As the discharge angle decreases toward the road surface, the risk area that could cause damage moves from the center of the vehicle to the rear; at a discharge angle of 90°, the range above 9.5 kW/m² was 1.59 m and 4.09 m to the front and rear of the vehicle, respectively. However, at a discharge angle of 30°, it was not generated at the front but was 10.39 m to the rear. In response to a hydrogen vehicle accident, first responders should perform rescue activities approaching from a diagonal direction to the vehicle front to minimize injury risk. This study can be used in future hydrogen vehicle design to develop the response strategy of the first responders.