Magnetic energy conversion

Abstract

In this study, magnetic and electromagnetic energy conversion of magnetocaloric materials (MCMs) and magnetic refrigeration, which is based on magnetocaloric effect (MCE), is presented in detail and made apprehensible. The MCE is defined as cooling or warming occurring in the magnetic material under adiabatic conditions when the external magnetic field is applied or removed from the magnetic material and vice versa. This result has been known as "adiabatic demagnetization" for years, though this phenomenon is a practical use of the MCE in magnetic materials. The magnetic materials demonstrate the MCE in the vicinity of their critical temperature. The magnetocaloric system is environmentally friendly and more efficient than conventional refrigeration cycle system based on vapor compression. Magnetic refrigeration is a cooling technology based on the MCE. This technique can be used to attain low temperatures, as well as the ranges used in common refrigerators. In magnetic and electromagnetic energy conversion, the coefficient of the performance (COP) for the system reaches 30-60% theoretical efficiency of the Carnot cycle. Magnetic refrigeration is being pursued using low magnetic fields near room temperature in hopes of enabling commercial devices using permanent magnets as the field source.In a magnetic refrigerator, a magnetocaloric heat pump is used as a cooling device based on MCMs, which are an ideal alternative to traditional compressor-based refrigeration technology. Theoretical studies demonstrate that refrigeration systems based on the MCE can be up to 35% more energy-efficient than vapor compression systems. Furthermore, cooling systems based on MCMs will operate with less noise due to the absence of a compressor. This technology makes use of water-based coolants instead of gaseous refrigerants. © 2018 Elsevier Inc. All rights reserved.