Magnetocaloric effect: A review of the thermodynamic cycles in magnetic refrigeration

Magnetic refrigeration (MR) at room temperature is an emerging technology and shows real potential to enter conventional markets. The principle of MR obeys the magnetocaloric effect (MCE), which is based on the effect caused by a magnetic field on the materials that bear the property of varying the magnetic entropy, as well as its temperature, when varying the magnetic field. This article revises the MCE, its theory and thermodynamics. It discusses the properties that must be met by the magnetocaloric materials as well as those most suitable for room temperature MR and those displaying a promising future. Finally, a presentation and description of the Carnot, Brayton, Ericsson, AMR and cascading MR cycles is given with a view to establishing selection criteria based on their performances.