Experimental Researches on the Performance of a Rotary-type Magnetic Refrigerator With Modified Double-Halbach Permanent Magnet Arrays

A room-temperature rotary-type magnetic refrigerator based on previous experiences was designed and constructed with a modified double-Halbach permanent magnet arrays. The average magnetic field provided by the modified magnet system ranged from 0.06 T to 1.40 T in the center region of the inner bore. This was fairly superior to the average value of previous magnetic arrays, which ranged from 0.3 T to 1.2 T. A series of Gadolinium-experiments have been done to investigate the system performance including no-load temperature span and cooling power. The results show the refrigerator with modified magnetic field obtained the better cooling performance at similar operating frequencies and utilization factors, when both ends of regenerator were kept adiabatic without heat exchangers. And the maximum no-load temperature span of 19.8 K was achieved at 1.25 Hz. With the heat exchangers added (the hot end temperature kept at 27.5℃), 10 W cooling power was obtained at 7 K temperature span, and the corresponding specific cooling power was about 47 W/kg. And the maximum cooling power of the measured is 50 W at 1.7 K temperature span.