Numerical study on hydrogen and thermal storage performance of a sandwich reaction bed filled with metal hydride and thermochemical material

Hydrogen storage and release process of metal hydride (MH) accompany with large amount of reaction heat. The thermal management is very important to improve the comprehensive performance of hydrogen storage unit. In present paper, thermochemical material (TCM) is used to storage and release the reaction heat, and a new sandwich configuration reaction bed of MH-TCM system was proposed and its superior hydrogen and thermal storage performance were numerically validated. Firstly, the optimum TCM distribution with a volume ratio (TCM in inner layer to total) of 0.4 was derived for the sandwich bed. Then, comparisons between the sandwich reaction bed and the traditional reaction bed were performed. The results show that the sandwich MH-TCM system has faster heat transfer and reaction rate due to its larger heat transfer area and smaller thermal resistance, which results in the hydrogen storage time is shortened by 61.1%. The heat transfer in the reaction beds have significant effects on performance of MH-TCM systems. Increasing the thermal conductivity of the reaction beds can further reduce the hydrogen storage time. Moreover, improving the hydrogen inflation pressure can result in higher equilibrium temperature, which is beneficial for the enhancing heat transfer and hydrogen absorption rates.