Presentation Information
[APP1-07]A Frictionless Sliding Mechanism for Reciprocating Magnetic Refrigeration Systems using Flux-Pinned Bulk HTSs
*Shinnosuke Matsunaga1, Takanori Motoki2 (1. National Institute of Technology, Gifu College (Japan), 2. Aoyama Gakuin University (Japan))
Keywords:
Magnetic Refrigerator,HTS Bulk,Magnetic levitation
The magnetocaloric effect is realized by varying the magnetic field applied to a magnetocaloric material (MCM). Magnetic refrigeration systems, which exploit this effect, are expected to be applied not only to hydrogen liquefiers but also to a wide range of cooling technologies. In a reciprocating-type magnetic refrigeration demonstrator, the variation of the magnetic field was achieved by changing the distance between the magnetic field source and the MCM. The superconducting magnet was fixed in place, while the MCM was driven axially by an actuator. As the MCM approaches the magnet, an attractive magnetic force acts between them, and one of the issues is how to support the resulting radial magnetic force. Previous studies have reported that small-scale experimental devices designed as precursors to scale-up demonstrators experienced radial forces as large as 1 kN. Without adequate support, these forces not only generate frictional heating in the cryostat but also cause wear of the contact components. To address these issues, we conceived a levitation mechanism based on flux pinning in bulk high-temperature superconductors (HTSs). Similar to demonstrations where a bulk HTS slides above a rail of permanent magnets, the bulk HTS can move freely along the longitudinal direction without resistance, so the actuator-driven motion is not hindered. This “sliding system” shares the cryogenic environment of the superconducting magnet and realizes a completely frictionless driving mechanism by dispensing with frictional contacts.