In recent years, hydrogen energy has been widely applied in various industries, but it may also bring a series of safety concerns. Especially in confined spaces like underground garages, where high-pressure hydrogen leaks can potentially cause combustion or explosions. To address this, this paper integrates numerical calculations and theoretical analysis to simulate the process of continuous high-pressure hydrogen leakage from hydrogen-powered vehicles within underground garages. Through investigating the influence of various parking space modes and the number of ventilation openings under mechanical ventilation conditions on hydrogen diffusion and distribution, it was discovered that, during the initial stages of leakage, the 2-parking space mode exhibited a slightly higher overall explosion risk in comparison to the 3- and 4-parking space modes. Notably, after 15 s, the 4-parking space mode shows the highest global explosion risk, while the 2-parking space mode consistently demonstrates the highest local explosion risk in the overhead space. Under mechanical ventilation, the number of ventilation openings significantly reduces hydrogen concentration over time. Specifically, after leakage cessation, increasing ventilation openings efficiently shortens the time required for hydrogen levels to drop to safe limits within the garage. The findings of this study can provide important references for the safety design of hydrogen fuel cell vehicle garages.

According to the provisions on fire separation distance between industrial and civil buildings in the latest 'General Code for Fire Protection of Buildings and Constructions' (GB 55037-2022). Radiant heat intensity is one of the main factors in calculating the fire separation distance between buildings. Therefore, the design process involves a lot of calculation of radiant heat intensity. This paper mainly studies the prediction model of radiant heat flux. Three different view factor calculation models, Mudan, Mudan-Sparrow, and Rai-Kalelkar, are used to evaluate the influence of key factors such as the diameter of the pool and the distance between the target and the center point of the liquid pool on the calculation results of radiant heat flux. The results show that when it came to estimating the radiant heat flux, the Mudan and Mudan-Sparrow models yielded comparable results. The calculation of the Rai-Kalelkar model shows that the radiant heat flux is about half of the heat flux in the first two models. When calculating the minimum fire separation distance for combustible liquid storage tanks with a fire dike, the results show that all three models can provide a larger safety margin than the point source model.

Since the corrosion defects in gas pipelines have similar corrosion characteristics to the surrounding soil, the random growth of these defects may be correlated, so we can not simply treat the corrosion defects as completely correlated or independent. Therefore, this paper proposes a method that can accurately calculate the failure probability of the pipeline system considering the correlation of corrosion defects: using MATLAB software to fit the parameters of the GEV model to select an appropriate distribution model; using Monte Carlo simulation (MC), considering different correlation coefficients and quantities, the system failure probability of pipeline corrosion defects is calculated; the results show that the system failure probability of the pipeline and the correlation coefficient are basically linear; when the correlation coefficient is increasing, the pipeline is regarded as an independent. There is a large error between the calculated failure probability of the series system and the actual result; the system failure probability of the pipeline increases with the increase of the assumed number of corrosion defects. When the correlation coefficient is greater than or equal to 0.6, the system failure probability of the pipeline increases significantly. An increase and the system failure probability of the pipeline decreases significantly.