Design and optimization of a magnet for magnetocaloric refrigeration

Abstract

The magnetic field source is the most expensive element of a magnetic refrigeration device. The design of an efficient magnet with high and low field regions, using reduced volumes of permanent magnets, is of paramount importance for the practical application of this new technology. A two-pole rotary magnet formed by sectors of oriented hard magnets and soft iron pieces is optimized in angular width and magnetization direction of each sector. A quadratic approximation is used for the optimization of the defining angles. This procedure provides the parameters that result in extreme values of a given functional F, defined as an efficiency variable of the working device. The procedure also gives the correlation between parameters and the relative importance of the deviations with respect to their mathematical optimal values. An optimized magnet has also been built, and the resulting calculated fields are compared with experimental measurements in the real system.

Caloric devices: A review on numerical modeling and optimization strategies

“…The listed objective variables only include , , , , cost, (average and maximum ), , and the magnet figures of merit and (for more information consult Refs. 72 and 85). The list includes the optimization of fluidic and solid‐state thermal caloric systems and magnet and regenerator magnetic systems.…”

“…One of the implementation using Python has resulted in a package dedicated to caloric systems 118 . Nevertheless, most of the research used software packages already available, such as COMSOL Multiphysics, 32 Ansys Fluent, 90,111 Ansys Maxwell, 82 Openfoam, 168 modelica, 169 Flux2D and Flux3D, 78 GMESH and GETDP, 85 and FEMM 83 …”

Simulation of a Hybrid Thermoelectric-Magnetocaloric Refrigerator with a Magnetocaloric Material Having a First-Order Transition

“…The magnetic field B is varied in a quasi-square wave form (see Section 4.4 below) between 0 and B 0 1.5 T, with a typical frequency ν = 0.5 Hz, but simulations were also undertaken with other frequencies. In this wave shape, the field has a constant minimum value of zero and a constant maximum value for two-fifths of the period each, and it changes between these extremes, with ramps of one tenth of the period, seeking to emulate an ideal adiabatic magnetization or demagnetization, but with a realistic rate of change, for a rotating magnet [18]. The discretization parameters were taken to be smaller and smaller until no substantially different results were found.…”

Investigation on the regenerative Brayton refrigeration cycle performances using novel Mn-Fe-P-Si composite material with thermal hysteresis as the working medium

“…The working process of a magnetic refrigerator does not produce any greenhouse gases, which is helpful to slow down the global warming. Therefore, this environment-friendly technology (Greco et al, 2019;Beltrán-López et al, 2019;Franco et al, 2018;Lei et al, 2018;Balli et al, 2017) is worthy to be deeply studied.…”