Performance optimization of metal hydride hydrogen storage reactors based on PCM thermal management

Abstract

Metal hydrides (MH) are considered promising hydrogen storage materials. In applications, the heat transfer characteristics of MH hydrogen storage reactors are closely related to their storage performance. Phase change materials (PCM) were proven to integrate with MH reactors for effective thermal management. Nevertheless, the PCM based MH reactors (MH-PCM reactors) still need to overcome the heat transfer resistance and the loss of volumetric hydrogen storage capacity caused by the PCM volume proportion. The present work established a mathematical model to describe the transfer and reaction process in the MH-PCM reactor. Various parameters were discussed in the current work. It was found that the increased PCM's amount and latent heat have a restricted effect on the enhancement of heat transfer and absorption reaction rate. The higher PCM's thermal conductivity and hydrogen supply pressure effectively enhanced the heat transfer and reaction rate. Furthermore, the increased absorption pressure can improve PCM's sensible heat storage capacity, which provides a new approach for optimizing PCM consumption. Finally, the quantitative relationship among the volumetric hydrogen storage capacity, the volume fraction and thermophysical properties of PCM, and the absorption pressure were established by systematic analysis, which provides an essential theoretical basis for the optimization of MH-PCM reactors.