abstract
Climate change and the increasing demand for energy globally have motivated the search for a more sustainable heat-pumping technology. Magnetic refrigeration stands as one of the most promising alternative technologies for clean and efficient heat pumps of the future. The rotating magnetocaloric effect (RMCE) has previously been studied in materials with magnetocrystalline anisotropy due to its potential to improve devices by requiring only a single magnetic field region, but these materials are fragile and costly to obtain, making them inviable for applications. It has been shown that by exploiting the demagnetizing effect, an RMCE is, in fact, attainable in any polycrystalline magnetocaloric sample with an asymmetric shape, without requiring magnetocrystalline anisotropy. Using gadolinium as a case study, we provide a theoretical framework for computing the demagnetizing field-based RMCE and present thorough experimental verification for different magnetic field intensities and a wide temperature range. Direct measurements of the RMCE in gadolinium reveal that a significant adiabatic temperature difference (1.2 K) and refrigerant capacity (7.44 J kg-1) can be attained within low magnetic field amplitudes (0.4 T). Utilizing lower magnetic field intensities in a magnetocaloric heat pump can significantly diminish the need for permanent magnet materials, thus reducing the overall device cost, size, and weight, ultimately enhancing the feasibility of mass-producing such devices.
keywords
ROOM-TEMPERATURE; MAGNETIC REFRIGERATOR; GADOLINIUM; BULK; 4-K
subject category
Energy & Fuels; Materials Science
authors
Almeida, R; Freitas, SC; Fernandes, CR; Kiefe, R; Araújo, JP; Amaral, JS; Ventura, JO; Belo, JH; Silva, DJ
our authors
Daniel José da Silva
Post-Doc Fellowship
João Cunha de Sequeira Amaral
Assistant Researcher
João Silva
Post-Doc FellowshipProjects
Demagnetizing-based magnetocaloric refrigeration (MAGCAL)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
The authors acknowledge Fundacao para a Ciencia e a Tecnologia (FCT) for the IFIMUP Projects UIDB/04968/2020, UIDP/04968/2020, PINFRA/22096/NECL/2016, NECL-NORTE-010145-FEDER-022096, CERN/FISTEC/0003/2019, PTDC/EME-TED/3099/2020. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MCTES (PIDDAC). R Almeida acknowledges FCT for the PhD Grant 2022.13354.BD. J H Belo also thanks EEA Grants for the funding via the Project FBR OC1 85 and FCT for his Contract DL57/2016 with Reference SFRH-BPD-87430/2012, DL 57/2016/CP1454/CT0013, with respective DOI 10.54499/DL57/2016/CP1454/CT0013.