Application of metal hydride sheet to thermally driven cooling system

This paper describes an application of a metal hydride (MH) sheet, which consists of MH powder, carbon fiber, and aramid pulp, in a metal hydride heat pump (MHHP) system with a TiFe0.9Ni0.1/La0.6Y0.4Ni4.9Al0.1 working pair (MH1/MH2). In the experiments, the effect of the use of MH sheet on the system performances was investigated, in which the MH sheets were used to replace part of the MH powder to improve the heat exchange performance. The sheets and powder were packed alternately into the MH beds in layers with an aspect ratio less than one. The MH sheet significantly accelerated the heat exchange ratio of both MH packed beds. Using the MH sheet in both reactors, the specific cooling power increased by 1.2 times. The results also indicated that the role of heat exchange in an MH2 reactor as a cooling output side was more important in the enhancement of system performance than that in an MH1 reactor as a heat source side. In addition, the proposed MH sheet was effective not only for improving the system performance but also for decreasing the stress on the reactor vessel due to the expansion of MH during the hydrogen absorption/desorption.