Three-dimensional modeling and simulation of hydrogen absorption in metal hydride hydrogen storage vessels

► We newly developed a three-dimensional hydrogen absorption model. ► Equilibrium pressure with the H/M ratio cannot be overlooked during absorption simulations. ► External S/V ratio of a MH vessel is a key factor to control the absorption performance. ► Higher H2 feeding pressure leads to a faster absorption reaction and a shorter charging time. In this paper, a three-dimensional hydrogen absorption model is developed to precisely study the hydrogen absorption reaction and resultant heat and mass transport phenomena in metal hydride hydrogen storage vessels. The 3D model is first experimentally validated against the temperature evolution data available in the literature. In addition to model validation, the detailed 3D simulation results show that at the initial absorption stage, the vessel temperature and H/M ratio distributions are uniform throughout the entire vessel, indicating that hydrogen absorption is very efficient early during the hydriding process; thus, the local cooling effect is not influential. On the other hand, non-uniform distributions are predicted at the subsequent absorption stage, which is mainly due to differential degrees of cooling between the vessel wall and core regions. In addition, a parametric study is carried out for various designs and hydrogen feed pressures. This numerical study provides a fundamental understanding of the detailed heat and mass transfer phenomena during the hydrogen absorption process and further indicates that efficient design of the storage vessel and cooling system is critical to achieve rapid hydrogen charging performance.