Making a Cool Choice: The Materials Library of Magnetic Refrigeration

Abstract

The phase‐down scenario of conventional refrigerants used in gas–vapor compressors and the demand for environmentally friendly and efficient cooling make the search for alternative technologies more important than ever. Magnetic refrigeration utilizing the magnetocaloric effect of magnetic materials could be that alternative. However, there are still several challenges to be overcome before having devices that are competitive with those based on the conventional gas–vapor technology. In this paper a rigorous assessment of the most relevant examples of 14 different magnetocaloric material families is presented and those are compared in terms of their adiabatic temperature and isothermal entropy change under cycling in magnetic‐field changes of 1 and 2 T, criticality aspects, and the amount of heat that they can transfer per cycle. The work is based on magnetic, direct thermometric, and calorimetric measurements made under similar conditions and in the same devices. Such a wide‐ranging study has not been carried out before. This data sets the basis for more advanced modeling and machine learning approaches in the near future.

Energy Applications of Magnetocaloric Materials

“…The most recent and most comprehensive review of magnetocaloric materials can be found in the work of Franco et al Another very important article on the material selection criteria was recently published by Gottschall et al The latest review of manganese‐based magnetocaloric materials was presented by Chaudhary et al, while another interesting publication was authored by Lyubina, who reviewed magnetocaloric materials with an adiabatic temperature change rate of higher than 2 K T –1 . Some older reviews are also available in the literature …”

“…The adiabatic temperature change and the isothermal entropy change of the magnetocaloric material should be correctly indicated under the cycling conditions and realistic conditions for any refrigeration or heat pumping system. This important fact actually concerns hysteretic materials and was excellently addressed in a recent publication by Gottschall et al This is also the reason why low‐cost and rare‐earth‐free Heusler alloys, despite having been the focus of intensive research, are currently not being considered for the development of magnetic refrigeration and heat pumping systems, except there are relevant new findings …”

“…Magnetocaloric materials are of two types based on the order of the phase transition between the ferromagnetic and paramagnetic states, namely, first-order magnetocaloric (FOMT) materials, which undergo discontinuous change in magnetization with changing temperature, and second-order magnetocaloric (SOMT) materials, which undergo continuous change in magnetization with changing temperature. [37,108,163] The most recent and most comprehensive review of magnetocaloric materials can be found in the work of Franco et al [36] Another very important article on the material selection criteria was recently published by Gottschall et al [37] The latest review of manganese-based magnetocaloric materials was presented by Chaudhary et al, [164] while another interesting publication was authored by Lyubina, [165] who reviewed magnetocaloric materials with an adiabatic temperature change rate of higher than 2 K T -1 . Some older reviews are also available in the literature.…”

“…The adiabatic temperature change and the isothermal entropy change of the magnetocaloric material should be correctly indicated under the cycling conditions and realistic conditions for any refrigeration or heat pumping system. This important fact actually concerns hysteretic materials and was excellently addressed in a recent publication by Gottschall et al [37] This is also the reason why low-cost and rare-earth-free Heusler alloys, despite having been the focus of intensive research, [181][182][183] are currently not being considered for the development of magnetic refrigeration and heat pumping systems, except there are relevant new findings. [44,184,185] Knowing that the magnetocaloric effect causes a large adiabatic temperature change for the smallest possible magnetic field change, which is mostly associated with the cost of the field source, it is important to also consider the environmental, resource, and geopolitical issues associated with the practical application of specific magnetocaloric materials.…”

“…Several researchers have concluded that caloric (ferroic) refrigeration and heat‐pumping technologies, which are still in the research and development phase, are the most important option for the future . These solid‐state technologies variously utilize magnetocaloric, electrocaloric, and mechanocaloric effects. A material that exhibits more than one of these effects is described as a multicaloric (multiferroic) material with multicaloric effects .…”