Demagnetizing fields in active magnetic regenerators

Kaspar Kirstein Nielsen (Invited author), Christian R.H. Bahl, Anders Smith

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A magnetic material in an externally applied magnetic field will in general experience a spatially varying internal magnetic field due to demagnetizing effects. When the performance of active magnetic regenerators (AMRs) is evaluated using numerical models the internal field is often assumed to be spatially constant and equal to the applied field, thus neglecting the demagnetizing field. Furthermore, the experimental magnetocaloric properties used (adiabatic temperature change, isothermal entropy change and specific heat) are often not corrected for demagnetization. The demagnetizing field in an AMR is in general both a function of the overall shape of the regenerator and its morphology (packed particles, parallel plates etc.) as well as the magnetization of the material. Due to the pronounced temperature dependence of the magnetization near the Curie temperature, the demagnetization field is also temperature dependent.
We propose a relatively straightforward method to correct sufficiently for the demagnetizing field in AMR models. We discuss how the demagnetizing field behaves in regenerators made of packed spheres under realistic operation conditions.
Original languageEnglish
Title of host publicationProceedings of the 6th IIF-IIR international Conference on Magnetic Refrigeration
Number of pages4
PublisherInternational Institute of Refrigeration
Publication date2014
Publication statusPublished - 2014
Event6th IIR/IIF International Conference on Magnetic Refrigeration - Fairmont Empress Conference Center, Victoria, Canada
Duration: 7 Sept 201410 Sept 2014


Conference6th IIR/IIF International Conference on Magnetic Refrigeration
LocationFairmont Empress Conference Center
Internet address


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