Abstract:
Metal hydride hydrogen storage is regarded as having broad application potential in the future hydrogen energy industry due to its safety and high hydrogen storage density. However, the hydrogen absorption and desorption processes are accompanied by intense exothermic/endothermic reactions. During cycling, hydrogen storage alloys are prone to repeated expansion and contraction, resulting in a decrease in thermal conductivity and a decline of hydrogen absorption and desorption performance. Therefore, thermal management technology is recognized as the critical element for enhancing hydrogen absorption and desorption performance. Research progress in metal hydride hydrogen storage reactors over recent years is summarized, with a focus on reactor geometry, modification of hydrogen storage materials, external cooling systems, and internal heat exchange structures including fins, circular tubes and helical tubes. Results show that reactors with different geometries exhibit distinct characteristics in heat transfer efficiency and space utilization. Doping high thermal conductivity media and optimizing the heat exchange structures are found to significantly improve temperature uniformity and to shorten hydrogen absorption and desorption time, while hydrogen storage capacity is reduced. Although external cooling systems can enhance the overall heat transfer capacity of the hydrogen storage reactor, internal cooling structures are regarded as more effective in alleviating local overheating. Complex fin structures and helical tube structures are demonstrated to excel in improving heat exchange efficiency and reducing temperature gradients. Although manufacturing cost and structural complexity remain application barriers, a solid foundation for the scaled application and engineering deployment of metal hydride hydrogen storage reactors is established by continuous innovation in thermal management technologies.