Optimization oriented design framework for magnesium-based metal hydride beds to enhance hydrogen storage performance

Magnesium-based solid-state hydrogen storage is promising for its high safety and high hydrogen capacity, but its low thermal conductivity, high operating temperature, and large reaction enthalpy necessitate effective optimization of metal hydride (MH) bed configuration and thermal management. Most existing studies overlook holistic design strategies that start from raw hydrogen storage powders to achieve comprehensively superior MH bed performance. This work proposes a unified optimization framework for magnesium-based MH beds and their thermal management systems. Using this framework, the impacts of thermal conductivity enhancement methods and thermal management schemes on hydrogen absorption behavior are systematically analyzed. Results demonstrate that increasing the length-to-diameter ratio improves heat conduction and reduces saturation time without sacrificing storage density. Compaction enhances volumetric hydrogen density, while metal foam (MF) incorporation most significantly boosts thermal conductivity. With 15 vol% MF, the thermal conductivity of the MH bed increases by 160 times, shortening absorption saturation time by 98.3% relative to the powder bed. The heat transfer efficiency of jacketed heat exchange is higher than that of embedded-tube heat exchange. Thermal management devices required for the powder MH bed demand a much higher power capacity than those for the compacted bed. This work provides a systematic, integrated design and optimization approach for high-performance magnesium-based MH beds and thermal management systems.