Performance Analysis of the Active Magnetic Regenerative Refrigerator with the Conduction Cooled HTS Magnet

Abstract

An active magnetic regenerative refrigerator (AMRR) with the conduction cooled high temperature superconducting (HTS) magnet is fabricated and experimentally investigated. Key components of the AMRR are two-stage multi-layered active magnetic regenerator (AMR), conduction cooled HTS magnet, and the helium gas flow system. Since magnetic refrigerants are only effective in the limited temperature range near their Curie temperatures, the layered structure with four magnetic materials (GdNi2, Gd0.1Dy0.9Ni2, Dy0.85Er0.15Al2, Dy0.5Er0.5Al2) is employed on the AMR to increase its temperature span. The AMR is designed to operate with the temperature range between 80 K and 20 K. The HTS magnet, being cooled down by a two-stage Gifford-McMahon (GM) cryocooler, produces maximum magnetic field of 3 T for the AMR. DC power supply, a solenoid current switch and an external dump resistor are used for a continuous ramping operation of the HTS magnet. Oscillating helium flow in the AMR is induced and controlled by the helium compressor and four solenoid valves. This paper presents the experimental results of the AMR system operating between 80.8 and 21.8 K and discusses technical issues on the results.