Numerical Investigation of Heat Transfer and Dehydrogenation in a Magnesium-Based Hydrogen Storage Tank Equipped with a U-Tube and H-Shaped Fin Heat Exchanger

The low thermal conductivity of magnesium-based metal hydride (MH) beds limits the dehydrogenation performance of hydrogen storage tanks, making effective thermal management essential. In this study, a three-dimensional multiphysics model of a magnesium-based hydrogen storage tank equipped with a U-tube and H-shaped fin heat exchanger was developed using COMSOL Multiphysics. The model couples heat transfer, hydrogen transport, and dehydrogenation kinetics, with the heat transfer fluid (HTF) represented by a convective boundary condition based on a turbulent correlation to investigate the effects of the initial MH bed temperature and HTF temperature on dehydrogenation behavior. The results show that the proposed heat exchanger provides continuous heat transfer pathways and improves temperature uniformity of the MH bed. Dehydrogenation initiates near the hydrogen outlet and gradually propagates throughout the tank. A higher initial MH bed temperature significantly accelerates the early-stage reaction, while a higher HTF temperature provides sustained heat input and shortens the time required to achieve high hydrogen conversion. These findings improve the understanding of coupled heat and mass transfer during dehydrogenation and provide theoretical guidance for the thermal management and design optimization of magnesium-based hydrogen storage tanks.