PROGRESS TOWARDS THE DEVELOPMENT OF HYDROGEN SORPTION CRYOCOOLERS FORSPACE APPLICATIONS

Sorption cryocoolers utilize metal hydride sorbent beds for the closed -cycle circulation of gaseous hydrogen through heat exchangers and a J oule-Thomson (J-T) expansion valve in order to achieve cold-stage temp eratures below 30K. These devices have high potential for satellite mi ssions that require long term reliability, minimal vibrations, and low operating power. Designs for nominal 25K liquid and 10K solid hydroge n refrigerators are described. Prototype hydride sorbent beds for brea dboard studies of sorption cryocoolers have been fabricated and tested to simulate expected operation. The sorbents contained in the beds ar e VHx, LaNi5-ySnyHx, and ZrNiHx. Some of these hydride beds have been integrated with a hydrogen J-T cold-stage. These experiments confirm t hat the selected metal hydrides and bed designs satisfy the constraint s associated with the proposed liquid and solid hydrogen cryocoolers. (C) 1997 International Association for Hydrogen Energy.