Cryogenic testing of an active magnetic regenerative refrigerator

Abstract

An AMR test apparatus has been developed for testing magnetic regenerators at temperatures ranging from room-temperature to 20 K. Near 300 K, no-load temperature spans over 80 K have been produced using regenerators composed of two and three different magnetocaloric materials. Modifications to the apparatus have been performed to allow testing at cryogenic temperatures. Initial tests near 80 K using magnetic fields of 5 T are presented using an AMR composed of Gd5Si0.33Ge3.67. A no-load temperature span of ∼8K is achieved. The operating point is established using liquid nitrogen flow through the shell-side of the warm heat exchangers of the AMR. Design characteristics of the test apparatus, problems encountered, and modifications for improving experimental results are discussed. © 2008 American Institute of Physics.