Towards powerful magnetocaloric devices with static electro-permanent magnets

Introduction: Magnetocaloric energy conversion represents an alternative to existing refrigeration, heat pump and energy harvesting technologies. A crucial part of a magnetocaloric device concerns the mag-netic field source. It uses mainly rare-earth materials and consists of moving parts and a drive system while displaying a limited energy efficiency and unavailability of fast and variable control of the magnetic field. Recent advances in efficient heat transfer for high-frequency magnetic cooling call for new devel-opments of magnetic field sources that can operate with high efficiency at high frequencies.Objectives: We report the concept of an electro-permanent magnetic (EPM) field source that efficiently recovers magnetic energy. In contrast to existing magnets, it allows very well-controlled operation with-out any moving parts. The main objective of this paper is to present a numerical and experimental study in which such an EPM was designed, built and tested.Methods: An extensive numerical investigation of the proposed design was carried out in terms of various geometrical and operating parameters. One of the design variations was built and experimentally evalu-ated for its energy efficiency and temperature increase at various operating frequencies.Results: We demonstrate an energy efficiency of these magnets of over 80% and operation with frequen-cies up to 50 Hz, which is crucial for future high-power-density and high-frequency magnetocaloric devices.Conclusions: Considering high energy efficiency at high operating frequencies, such EPMs would allow for miniaturization, making them a viable option for future compact magnetocaloric devices.(c) 2023 The Authors. Published by Elsevier B.V. on behalf of Cairo University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).