Performance evaluation of the magnetothermal properties of GGG and ErAl2 packed beds at cryogenic temperatures

• Numerical and experimental analysis of GGG and ErAl 2 at 4.2–20 K. • Comparison of heat transfer models for cryogenic magnetocaloric materials. • Insights into magnetic refrigeration development. • Single-blow testing reveals material-specific thermal behavior. The development of high-temperature superconductors (HTS) has highlighted the need for advanced cryocooling technologies capable of achieving high efficiency at extremely low temperatures. Among the various cooling techniques, magnetic refrigeration has emerged as a promising method due to its potential for high Carnot efficiency at temperatures corresponding to liquid helium and liquid hydrogen. A test stand has been developed to evaluate the heat transfer dynamics and the magnetocaloric effect of packed beds of magnetocaloric materials. This article presents the results and analysis of the testing of two magnetocaloric materials, Erbium Aluminum II (ErAl 2 ) and Gadolinium Gallium Garnet (GGG), in the range of 4.2–20 K. The recorded temperatures measurements are compared with numerical predictions for different fluid mass flow rates, temperatures, and magnetic field values. Insights gained from the testing will be used to develop a scaled magnetic refrigerator based on both materials.