Computational analysis of the hydrogen dispersion in semi-confined spaces

Although green hydrogen is an appropriate clean energy alternative, hydrogen leakage and dispersion are the challenges to establishing safe and reliable hydrogen infrastructure. Released hydrogen in confined or semi-confined space may build up flammable gas clouds, which can have severe consequences for the safety of human life and property. Proper ventilation systems will help in reducing hydrogen gas accumulation. This study presents a comprehensive study to analyse hydrogen dispersion behaviour and the influence of ventilation variations on hydrogen volumetric concentration and stratification. A computational model is developed for the leakage diffusion of hydrogen in an enclosed cuboid space with roof and door ventilation. A detailed analysis is conducted to shed light on the impact of door and roof ventilation positions on forming the flammable cloud. It is observed that the displacement flow and multi-layer stratification are established in the absence of wind or imperceptible air circulation. Single-vent configurations were ineffective, when installed at the top of the leakage point, but multiple-vent arrangements incorporating door and roof vents were found to be more efficient in extracting hydrogen. However, it should be noted that not all multiple-vent arrangements may meet safety requirements. The result indicated that the optimal arrangement for minimizing the size of a flammable cloud involves placing the door vent close to the ceiling while situating the roof vent near the source of leakage. These findings will aid in devising strategies for minimizing the occurrence of flammable cloud formation and preventing hydrogen fire and explosion incidents within partially enclosed facilities.