A versatile magnetic refrigeration demonstrator

Abstract

A versatile room temperature reciprocating magnetic refrigeration demonstrator has been designed, built and tested in order to check suitable magnetocaloric materials for magnetic refrigeration. Test experiments have been done with 31 g of Gd spheres of 0.2 – 0.4 mm diameter as refrigerant material, because it is a well-known benchmark material for magnetic refrigeration. The magnetic field is provided by a Halbach Nd2Fe14B permanent magnet with a slot of 10 mm width and a maximum field of 1.4 T. At optimized values of frequency (f = 0.7 Hz) and utilization factor (U = 0.19), the demonstrator achieves a maximum no load temperature span of 19.3 K. A maximum cooling power of 6 W at zero temperature span was obtained at optimized values f = 0.31 Hz and U = 1.1. Different thermodynamic cycles have been studied looking for the optimized parameters.