Magnetocaloric materials for hydrogen liquefaction produced by rotating disk atomization

Abstract

Magnetic refrigeration has long been pursued due to its highly efficient refrigeration cycle and low environmental impact made possible by the magnetocaloric effect . While much of the research on magnetocaloric materials has been focused on the pursuit of near room temperature refrigeration, this green and efficient cooling process has the potential for great impact in cooling at cryogenic temperatures, specifically for the liquefaction of gases such as methane, oxygen, and hydrogen. Some of the major challenges to realizing this potential are identifying the materials exhibiting a strong MCE in the desired temperature range and the economic production of these materials in a form suitable for use in a refrigeration system. The research presented here meets these challenges by identifying and analyzing rare-earth-based magnetocaloric materials to enable magnetic refrigeration from room temperature to sub 100 K.A list of preliminary compositions was selected based on literature search and linear extrapolation. A series of samples were synthesized and characterized to refine the preliminary compositions based on their Curie temperature and adiabatic temperature changes. The downselected materials were synthesized in spherical powder form with particles ranging from 150 to 250 m using the Rotating Disk Atomization technique. The obtained powders have been contributed to be assembled into a regenerator and tested in a proof-of-concept hydrogen liquefaction system designed by collaborators at Pacific Northwest National Laboratory.