The prototype of a cryogenic magnetic refrigerator based on a cryomagnetic system with a 10 T superconducting coil

摘要

The concept of a magnetic refrigerator at cryogenic temperatures below the temperature of liquidnitrogen based on a reciprocating mechanism was considered (Mashirov et al., 2018). This type ofdesign implies that a mechanical heat switch will be used, in contrast to the well-known cryogenicmagnetic refrigerator, in which gaseous helium is used as heat keys (Park et al., 2017). Theoretically, itwas estimated that the amount of heat obtained as a result of the magnetocaloric effect will betransferred due to thermal conductivity to the hot and cold heat exchanger in a time of about 1 s.Ponderomotive forces will be equal to values of about 70 N. The aim of this work was to create aprototype of a single magnetic cooling cycle based on a cryomagnetic system with a superconductingcoil with a magnetic field induction of 10 T and with the possibility of maintaining the temperature ofthe working body of a magnetic refrigerator from 2 K to 300 K. The superconducting magnet was madebased on the superconducting Nb3Sn coil. Using a Hall sensor measurements of the magnetic field werecarried out the maximum value of the induction was 10+/-1% T. The prototype of the magneticrefrigerator is located in the mine of the superconducting magnet, the diameter of the mine is 29 mm. Asample of a polycrystalline DyNi2 alloy with a Curie ferromagnetic point Tc = 23 K was used as amagnetocaloric working body. In this design of the magnetic refrigerator mechanical heat switche`swere used. The dependence of the thermal resistance of mechanical heat keys on the heat transfersurface was separately investigated. This paper presents the results of modeling and preliminaryexperiments to determine the thermodynamic characteristics of a prototype of a single cycle magneticrefrigerator of the reciprocating type based on the DyNi2 alloy, the aforementioned superconductingmagnet up to 10 T and a cryostat of 2-300 K. The reported study was funded by RFBR to the researchproject No. 18-07-01321 and partially was carried out within the framework of the state task.