抄録
The development of magnetic refrigerants and basic research on active magnetic regenerative (AMR) refrigeration at room temperature were performed. Temperature differences between the hot and cold ends of the AMR unit of more than 45 degrees, and achieving the lowest temperature of minus 10 degrees were obtained by operating the AMR cycle with a NdFeB Halbach-type permanent magnet and spherical-shaped GdY magnetic refrigerants. In the case of the La(Fe,Co,Si)13 compound, the temperature difference between the ends of the AMR unit reached only 21 degrees. This is mainly attributed to the fact that larger specific heat provides smaller temperature changes in the magnetocaloric effect even if the La(Fe,Co,Si)13 compound shows larger magnetic entropy change than Gd alloys. At the same time, large specific heat is effective for load characteristics. Model calculations indicated that multi-layered magnetic refrigerants whose magnetic transition temperatures are tailored to the temperature gradient in the AMR unit improve both temperature difference and load characteristics. Ideal design for achieving optimized heat flow and regeneration leads to the room-temperature application.
