The impact of fuel cell vehicle exhaust grille shape under natural ventilation on hydrogen leakage and diffusion

The rapid progression of hydrogen fuel cell vehicles has brought forth various challenges, primarily the frequent occurrence of hazardous incidents stemming from hydrogen leakage and diffusion. Consequently, there is a growing emphasis on hydrogen safety, leading to the development of stricter standards and regulations to mitigate the associated safety risks. Research on the design of exhaust port structures to facilitate the safe diffusion of hydrogen after leakage in diverse scenarios has become increasingly significant. This study examines the impact of exhaust grille shapes on hydrogen leakage and diffusion phenomena within the hydrogen storage compartment of fuel cell vehicles under natural ventilation conditions. Five distinct porous grille shapes were examined: rectangular, circular, square, rhombic, and hexagonal grilles. Numerical simulations of hydrogen leakage and diffusion within the compartment were conducted using Cradle scFLOW software. The effectiveness of the different grille shapes was assessed using several criteria, including average hydrogen molar fraction, pressure drop (indicative of negative pressure regions), density, and Richardson number. Overall, the rectangular grille exhibited superior performance in facilitating hydrogen venting.