Study on Hydrogen Leakage, Explosion and Safety Protection in an Underground Parking Garage

To investigate the hydrogen leakage dispersion and explosion characteristics of fuel cell vehicles in an underground parking garage, experimental and numerical simulation studies were conducted. The results show that the hydrogen leakage concentration exhibits an evolutionary pattern of a rising stage followed by a plateau stage, with a stratified distribution characterized by higher concentration at the top and lower concentration at the bottom. Higher leakage flow rate leads to a faster concentration growth rate, while the two are not in a direct proportional relationship. The hydrogen concentration near the leakage outlet was relatively low. The maximum explosion overpressure reached 194 kPa at a hydrogen concentration of 20%, with higher overpressure observed on the walls. Flame propagation followed a four-stage law, and a Laval nozzle effect appeared at the leakage outlet. Ventilation can rapidly suppress hydrogen accumulation, and the ventilation effect approached optimality at a wind speed of 8 m/s. The explosion venting area exerted the most significant influence: when the venting area increased from 0.36 m2 to 1.44 m2, the overpressure decreased by 76%. The explosion venting position was the second most influential factor, while the vent shape had negligible effects. This study provides a scientific basis for the safety prevention and control of hydrogen energy applications in underground spaces.