Thermal Management in Hydrogen Storage Tanks Using Metal Hydrides and Phase Change Materials

Metal hydrides (MHs) are regarded as highly desirable substances for both fixed and mobile hydrogen storage applications. Given that the hydrogenation and dehydrogenation of metal hydrides are exothermic and endothermic processes that involve substantial heat exchange, precise temperature control is essential. Various methods, including the use of phase change materials (PCMs), have been employed to manage this thermal behavior effectively. In this study, sodium nitrate (NaNO3) was utilized in different geometric configurations to store the heat generated during the reaction of Mg2Ni with hydrogen. Computational fluid dynamics (CFD) methods were used to conduct the study. Therefore, three distinct geometries were designed to evaluate the performance of PCM and MH beds to reduce the bed temperature and enhance the reacted concentration of hydrogen within the bed. By increasing PCM-to-MH volume percent from 1 to 18 during absorption, the bed temperature decreases from 627 to 620 K for Case B and 590 K for Case C within 10,000 s. In addition, the maximum reacted hydrogen for three cases (A, B, and C) are 0.12, 0.8, and 1, respectively. Finally, the desorption process was performed using NaNO3 and the reacted concentration in cases A, B, and C became 0.17, 1 and 1, respectively.