Design and Performance Study of a Permanent-Magnet Rotary Refrigerator Demo

Magnetic refrigeration utilizes the magnetocaloric effect to exchange heat. The magnetocaloric effect is a phenomenon in which a temperature change is caused in a magnetocaloric material by a change of magnetic field. In this project a small scale permanent-magnet rotary refrigerator has been designed to demonstrate the magnetocaloric effect and how it can be used for practical purposes. The design consists of custom magnetic assemblies, a rotating disk to hold the magnetocaloric material, the magnetocaloric material itself, a motor to rotate the disk and supply the work needed to create the temperature difference, resistance temperature detectors to monitor temperature changes, and a support structure. The magnetocaloric material is pure (99.9%) Gadolinium powder. The required magnetic intensity change is 1.0T which allows the Gadolinium powder to have a measurable temperature change of approximately 2 ºC. The magnetic field is produced by a magnetic assembly consisting of 2 inch N52 neodymium magnet cubes and soft iron flux-concentrators. The rotary disk design allows a direct input work from the motor and produces quiet operation. The details of the design and its performance are presented.