The development of a compact refrigeration system using metal hydrides 1st report: to decide the specification of the MH refrigeration system and mechanism of hydriding reaction by MH{sub}(High) (Ti{sub}0.18Zr{sub}0.84Cr{sub}1.0Fe{sub}0.7Mn{sub}0.3Cu

摘要

The MU refrigeration systems are regarded as important and compact ones for solving energy and environmental issues. Our purposes are to develop the compact refrigeration system for the vending machine and the show case using MH, and to attain a refrigeration temperature of 243K by using a heat source of 403-423K. The kinetics of MU hydriding and dehydriding reactions is of importance relative to their practical use as a refrigerator system. The kinetics of the reaction between hydrogen and MH{sub}(High) (Ti{sub}0.18Zr{sub}0.84Cr{sub}1.0Fe{sub}0.7Mn{sub}0.3Cu{sub}0.057) has been followed in this paper. A relatively rapid absorption of hydrogen takes place for values of relative composition to about 0.3-0.4. It is evident that a hydrogen diffusion plays a minor role during this stage, as that part of the metal not covered by hydride is always in contact with hydrogen. The direct chemical reaction between the hydrogen and the exposed metal surface is therefore postulated as the rate-controlling process. The rate of the reaction then decreases, and for values of relative composition above about 0.8, the reaction becomes slow. After the metal particles have been completely covered by a hydride layer, the transport of materials through the layer by diffusion becomes rate controlling process.