Comparing superconducting and permanent magnets for magnetic refrigeration

Rasmus Bjørk; Kaspar Kirstein Nielsen; C. R. H. Bahl; Anders Smith; Anders Christian Wulff

doi:10.1063/1.4943305

Comparing superconducting and permanent magnets for magnetic refrigeration

Rasmus Bjørk, Kaspar Kirstein Nielsen, C. R. H. Bahl, Anders Smith, Anders Christian Wulff

Department of Energy Conversion and Storage

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Abstract

We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio of the regenerator and desiredinternal magnetic field. It is shown that to produce a 1 T internal field in theregenerator a permanent magnet of hundreds of kilograms is needed or an area ofsuperconducting tape of tens of square meters. The cost of cooling the SC solenoidis shown to be a small fraction of the cost of the SC tape. Assuming a cost ofthe SC tape of 6000 $/m² and a price of the permanent magnet of 100 $/kg, thesuperconducting solenoid is shown to be a factor of 0.3-3 times more expensive thanthe permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspectratio of the regenerator. This factor decreases for increasing field strength, indicatingthat the superconducting solenoid could be suitable for high field, large coolingpower applications.

Original language	English
Article number	056205
Journal	A I P Advances
Volume	6
Issue number	5
Number of pages	6
ISSN	2158-3226
DOIs	https://doi.org/10.1063/1.4943305
Publication status	Published - 2016

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title = "Comparing superconducting and permanent magnets for magnetic refrigeration",

abstract = "We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio of the regenerator and desiredinternal magnetic field. It is shown that to produce a 1 T internal field in theregenerator a permanent magnet of hundreds of kilograms is needed or an area ofsuperconducting tape of tens of square meters. The cost of cooling the SC solenoidis shown to be a small fraction of the cost of the SC tape. Assuming a cost ofthe SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, thesuperconducting solenoid is shown to be a factor of 0.3-3 times more expensive thanthe permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspectratio of the regenerator. This factor decreases for increasing field strength, indicatingthat the superconducting solenoid could be suitable for high field, large coolingpower applications. ",

author = "Rasmus Bj{\o}rk and Nielsen, {Kaspar Kirstein} and Bahl, {C. R. H.} and Anders Smith and Wulff, {Anders Christian}",

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T1 - Comparing superconducting and permanent magnets for magnetic refrigeration

AU - Bjørk, Rasmus

AU - Nielsen, Kaspar Kirstein

AU - Bahl, C. R. H.

AU - Smith, Anders

AU - Wulff, Anders Christian

PY - 2016

Y1 - 2016

N2 - We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio of the regenerator and desiredinternal magnetic field. It is shown that to produce a 1 T internal field in theregenerator a permanent magnet of hundreds of kilograms is needed or an area ofsuperconducting tape of tens of square meters. The cost of cooling the SC solenoidis shown to be a small fraction of the cost of the SC tape. Assuming a cost ofthe SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, thesuperconducting solenoid is shown to be a factor of 0.3-3 times more expensive thanthe permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspectratio of the regenerator. This factor decreases for increasing field strength, indicatingthat the superconducting solenoid could be suitable for high field, large coolingpower applications.

AB - We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio of the regenerator and desiredinternal magnetic field. It is shown that to produce a 1 T internal field in theregenerator a permanent magnet of hundreds of kilograms is needed or an area ofsuperconducting tape of tens of square meters. The cost of cooling the SC solenoidis shown to be a small fraction of the cost of the SC tape. Assuming a cost ofthe SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, thesuperconducting solenoid is shown to be a factor of 0.3-3 times more expensive thanthe permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspectratio of the regenerator. This factor decreases for increasing field strength, indicatingthat the superconducting solenoid could be suitable for high field, large coolingpower applications.

U2 - 10.1063/1.4943305

DO - 10.1063/1.4943305

M3 - Journal article

VL - 6

JO - A I P Advances

JF - A I P Advances

SN - 2158-3226

IS - 5

M1 - 056205

ER -

Comparing superconducting and permanent magnets for magnetic refrigeration

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