Room-temperature magnetic refrigeration: from basic research to development for application.

Cooling properties of active magnetic regenerative (AMR) refrigeration using spherical magnetic refrigerant particles of Gd alloys and La(Fe,Si)13-based compounds were investigated by a primitive test apparatus for the AMR-cycle refrigeration. The maximum temperature difference of 46°C and the lowest cold-end temperature of −11°C were obtained by AMR-cycle operation using a single refrigerant material, GdY alloy, under a magnetic field of 1.1 tesla. La(Fe,Si)13-based refrigerants showed high tolerance for heat load due to their large heat capacity although the temperature difference (ΔT) using La(Fe,Si)13-based refrigerants was only half that using GdY-alloy refrigerants. Model calculation of AMR cycle indicates that layered La(Fe,Si)13-based refrigerants having different TC would be effective to enlarge ΔT and obtain good heat-load properties at the same time. In the AMR cycle, the potential coefficient of performance is expected to reach 5 under the condition of heat load of tens of watts with the ΔT ~25°C and f ~1 Hz using 1 kg of magnetic refrigerant.