Measurement and the improvement of effective thermal conductivity for a metal hydride bed – a review

Solid-state hydrogen storage based on metal hydrides is considered a promising method for hydrogen storage. However, the low inherent thermal conductivity of metal hydride powder significantly limits the hydrogenation/dehydrogenation process in the metal hydride bed. Accurate measurement and improvement of the effective thermal conductivity of a hydride bed is of great significance for design of solid-state hydrogen storage devices. This article analyzes the factors that influence the effective thermal conductivity of a metal hydride bed, and also introduces different measurement methods and improvement ways for the effective thermal conductivity of a metal hydride bed. It is an effective way to improve the thermal conductivity of metal hydride beds by hydride powder mixed with a high thermal conductivity material and compaction. Accurately measuring the influence of hydrogen pressure, temperature and hydrogen storage capacity and other factors on the effective thermal conductivity of a metal hydride bed and obtaining the numerical equation of effective thermal conductivity play an important role in guiding the optimization design of heat and mass transfer structure of metal hydride hydrogen storage devices. The transient plane source method seems to be a better measurement choice because of short test time and easy to establish a pressure-tight and temperature control test system. However, there is still a lack of testing standards for the thermal conductivity of the hydride bed, as well as suggestions for the selection of test methods, improvement ways and design of in situ test room.