Analysis of the fire hazard and leakage explosion simulation of hydrogen fuel cell vehicles

With the development of hydrogen fuel cell vehicles, the problem of fire danger is a major event that cannot be ignored. The present research adopts a combination of theoretical analysis and numerical simulation. The fire hazard of hydrogen fuel cell vehicles is analyzed by the FMEA and risk matrix, and according to the hazard analysis results, the key indicators and scenarios were selected to be numerically simulated by FLACS. It is found that the main reason for the fire or explosion of hydrogen fuel cell vehicles is the failure of hydrogen supply pipelines and valves, and the hydrogen leakage and diffusion in the tunnel will be affected by the leakage direction, leakage site, and ambient wind. The fire hazard of leaks in the vertical direction is greater than that in the horizontal direction. The fire hazard is highest when the leak direction is vertically downward with a maximum combustible cloud volume of 107.4 m3. Longitudinal ventilation in the tunnel is more conducive to the diffusion of hydrogen, which can effectively reduce the fire risk of hydrogen leakage. When the wind speed is 1 m/s, 3 m/s, 5 m/s, and 7 m/s, the maximum volume of the combustible cloud is 73.27 m3, 51.78 m3, 45.67 m3, 40.12 m3. It can be found that after the wind speed is increased to 5, the effect of reducing the volume of combustible clouds is no longer obvious, so the most economical and suitable longitudinal ventilation speed of the tunnel is 3 m/s ∼ 5 m/s. An explosion occurs immediately when the leaking gas cloud is ignited. The temperature of the explosion after igniting the leaked gas cloud is affected by the concentration and range of the gas cloud before ignition, which is higher in the part with high concentration and large gas cloud range. The pressure in the tunnel is much less than atmospheric pressure, which will not cause overpressure damage to the human body. The analysis results of this study provide a basis for the key points that hydrogen fuel cell vehicles should pay attention to in the safety design, and provide a data reference for the fire ventilation design in the tunnel.