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This study explores the safety problems of hydrogen leakage and explosion in hydrogen fuel cell buses through Computational Fluid Dynamics simulations. The research investigates the diffusion behavior of hydrogen in the passenger cabin depending on the leakage position and flow rates, identifying a stratified, constant-concentration layer formed at the top of the cabin. Leakage near the rear wall of the vehicle provided the highest hydrogen concentration, while at higher flow rates, the diffusive process accelerated the spreading of flammable hydrogen concentrations. Hydrogen ignition simulations showed a fast internal pressure increase and secondary explosions outside the vehicle. Thermal hazards in the cases were higher than overpressure. The research’s additional analysis of ignition timing and source location shows that overpressure peaked initially with delayed ignition but declined afterward, while rear-ignited flames exhibited the farthest high-temperature hazard range at 10.88 m. These findings are fundamental for giving insight into hydrogen behavior in confined spaces and thus guiding risk assessment and emergency response planning for the development of safety protocols in hydrogen fuel cell buses, contributing to the safer implementation of hydrogen energy in public transportation.

As a carbon-free clean energy source and energy carrier, the risk of hydrogen explosion is one of the major problems in industrial production processes and has attracted a lot of attention from research scholars. According to the records in the Web of Science Core Collection database, a total of 1043 articles or reviews related to hydrogen explosion were published from 2001 to 2021. In this study, the collected literature information was visually analyzed using VOSviewer and CiteSpace. The results show that China, USA, Germany, and Japan are major contributors to hydrogen explosion research; the International Journal of Hydrogen Energy has the highest publications among all source journals. The research theme of hydrogen explosion has developed into two main directions: hydrogen mixture explosion characteristics and suppression methods, hydrogen explosion characteristics and suppression methods. Compared to traditional suppression methods, fine water mist is more efficient and environmentally friendly for the explosion of hydrogen and its mixtures. New research hotspots have appeared related to hydrogen fuel cells, the mechanism and prediction method of hydrogen VCE and DDT, explosive suppressants with engineering practicality and economy, and numerical methods that can accurately simulate the turbulence of hydrogen combustion. The results of the study can be used to help researchers quickly understand the current status and research frontiers of hydrogen explosion research and contribute to further research in the field.

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 the development of hydrogen energy, containerized hydrogen fuel cell systems are being used in distributed energy-supply systems. Hydrogen pipelines and electronic equipment of fuel cell containers can trigger hydrogen-explosion accidents. In the present study, Computational Fluid Dynamics (CFD) software was used to calculate the affected areas of hydrogen fuel cell container-explosion accidents with and without protective walls. The protective effects were studied for protective walls at various distances and heights. The results show that strategically placing protective walls can effectively block the propagation of shock waves and flames. However, the protective wall has a limited effect on the reduction of overpressure and temperature behind the wall when the protective wall is insufficiently high. Reflected explosion shock waves and flames will cause damage to the area inside the wall when the protective wall is too close to the container. In this study, a protective wall that is 5 m away from the container and 3 m high can effectively protect the area behind the wall and prevent damage to the container due to the reflection of shock waves and flame. This paper presents a suitable protective wall setting scheme for hydrogen fuel cell containers.

Hydrogen is a potential key component of a carbon-neutral energy carrier and an input to marine industrial processes. This study examines the consequences of coupled hydrogen release and marine environmental factors during floating photovoltaic hydrogen production (FPHP) system failures. A validated three-dimensional numerical model of FPHP comprehensively characterizes hydrogen leakage dynamics under varied rupture diameters (25, 50, 100 mm), transient release duration, dispersion patterns, and wind intensity effects (0–20 m/s sea-level velocities) on hydrogen–air vapor clouds. FLACS-generated data establish the concentration–dispersion distance relationship, with numerical validation confirming predictive accuracy for hydrogen storage tank failures. The results indicate that the wind velocity and rupture size significantly influence the explosion risk; 100 mm ruptures elevate the explosion risk, producing vapor clouds that are 40–65% larger than 25 mm and 50 mm cases. Meanwhile, increased wind velocities (>10 m/s) accelerate hydrogen dilution, reducing the high-concentration cloud volume by 70–84%. Hydrogen jet orientation governs the spatial overpressure distribution in unconfined spaces, leading to considerable shockwave consequence variability. Photovoltaic modules and inverters of FPHP demonstrate maximum vulnerability to overpressure effects; these key findings can be used in the design of offshore platform safety. This study reveals fundamental accident characteristics for FPHP reliability assessment and provides critical insights for safety reinforcement strategies in maritime hydrogen applications.

The purpose of the study is to determine numerically the height of a wall designed to protect people from the negative effects of a blast wave, ensuring a specified level of safety. An accidental explosion of a hemispherical hydrogen-air stoichiometric cloud is considered. Near the epicenter of the accident, a person is subjected to shock-impulse loading as the blast wave front passes. A protective wall is installed between the accident’s epicenter and the person’s location to mitigate the explosion’s impact on human health. The wall’s transverse size (width) is sufficiently large to ensure that it does not affect the safety of a person whose location remains unchanged. The required height of the protective wall can be determined by solving an inverse problem in gas dynamics, focusing on the movement of a multi-component mixture of hydrogen combustion products through the surface layer of the atmosphere at the accident site. The gas flow disturbed by the explosion collides with the wall barrier, partially reflects off the wall, and moves around it in a vertical longitudinal plane, exerting a baric effect on a person. Solving the combined gas-dynamic and safety problem of human damage by a blast wave helps determine whether the current height of the protective wall is sufficient to ensure a safe level of conditional probability of human damage. A series of computational experiments were conducted for different heights of the protective structure using the mathematical model of a gas explosion and probit analysis. As a result, the relationship between the conditional probability of human injury and the vertical size of the wall was established in the form of a plot. Using this plot, a safety expert can determine the required wall height to ensure a sufficient level of human safety in the event of a hydrogen explosion accident.

The effect of different obstacle positions on the explosion flame dynamics of hydrogen-air mixtures with concentration gradients is investigated by numerical simulations. The numerical simulations predict explosion characteristic parameters matching correctly with the experimental results. The calculation results show that the influence of the obstacle position on the explosion flame of an inhomogeneous mixture is more significant compared to that of a homogeneous mixture. The analysis of the flame morphology and flow field reveals that, as the obstacle position increases, the premixed flame undergoes more complex deformation after passing through the obstacle and generates eddies near the obstacle under the action of vortices. By comparing the flame front position and peak overpressure after the explosion, it is found that, as the obstacle position increases, the concentration gradient has a stronger inhibitory effect on flame propagation. The influence of the concentration gradient on the peak overpressure is more pronounced when the obstacle is 200 mm from the ignition point. This research can provide theoretical guidance for industrial explosion protection and safety management.

Background Issues of hydrogen explosion safety are extremely relevant. Search for solutions requires both experimental and computational methods. Aim To experimentally study the turbulent combustion of hydrogen-air mixtures and to test the CABARET-COMBUSTION CFD calculation code using the obtained data. Materials and methods The study includes experiments conducted in a facility representing a large diameter pipe, as well as numerical simulation of deflagration combustion. Results The calculated data on the flame front propagation velocity and pressure dynamics at the shock wave front are consistent with experimental results. Conclusion The obtained results indicate the potential of using the CABARET-COMBUSTION CFD code in the numerical solution of hydrogen-air mixture combustion problems. This code and its testing on data obtained with high-quality diagnostics will increase the predictive capabilities of supercomputer simulation for the analysis of hypothetical accidents at a qualitatively new level.

For the safe utilization and management of hydrogen energy within a fuel-cell room in a hydrogen-fueled house, an explosion test was conducted to evaluate the potential hazards associated with hydrogen accident scenarios. The overpressure and heat radiation were measured for an explosion accident at distances of 1, 2, 3, 5, and 10 m for hydrogen–air mixing ratios of 10%, 25%, 40%, and 60%. When the hydrogen–air mixture ratio was 40%, the greatest overpressure was 24.35 kPa at a distance of 1 m from the fuel-cell room. Additionally, the thermal radiation was more than 1.5 kW/m2, which could cause burns at a distance of 5 m from the hydrogen fuel-cell room. Moreover, a thermal radiation in excess of 1.5 kW/m2 was computed at a distance of 3 m from the hydrogen fuel-cell room when the hydrogen–air mixing ratio was 25% and 60%. Consequently, an explosion in the hydrogen fuel-cell room did not considerably affect fatality levels, but could affect the injury levels and temporary threshold shifts. Furthermore, the degree of physical damage did not reach major structural damage levels, causing only minor structural damage.

This study aims to present computational technology that can be used to evaluate numerically the harmful environmental consequences caused by an accidental hydrogen release from failed high-pressure dispensing cylinders and its explosion at a vehicle hydrogen filling station. A coupled problem of a hydrogen explosion products expansion in the atmospheric ground layer and a harmful explosion pressure wave shock impact on service personnel and infrastructure buildings at an accident site is solved by means of computer experiment simulation series. A spatial time-dependent model of compressible hydrogen-air mixture flow is used to obtain pressure history in calculation area in order to assess maximum overpressure in control points of human possible locations and on building surfaces exposed to hydrogen blast wave impact. A deterministic impact consequences model is based on comparing maximum overpressure values extracted from the mathematical model with threshold ranges corresponding to certain degrees of human damage and infrastructure destruction. The presented computer technology allows safety experts to identify potentially dangerous zones by means of mathematical modelling and recommend effective protection measures to mitigate negative consequences of explosions.