Abstract
Thermal control elements, i.e., thermal diodes, switches, and regulators, can control the heat flow in an analogous way in how electronic devices control electrical currents. In particular, a thermal diode allows a larger heat flux in one direction than in the other. This has aroused the interest of researchers working on the thermal management of electronics, refrigeration, and energy conversion. Solid-state thermal diodes are attractive because they are silent, reliable, lightweight, and durable. While some solid-state thermal diodes have been developed at the nano- and microscale, the leap to the macroscale has yet to be made. A macroscale thermal diode would play a crucial role in the future development of applications related to caloric refrigeration and heat pumping. Additionally, the temperature changes of caloric materials (due to the caloric effect) are ideal for testing these thermal devices. This paper aims to numerically evaluate the influence of a macroscopic solid-state thermal diode in a magnetocaloric refrigeration device under transient and quasi-steady-state conditions. Materials with different temperature-dependent properties were analyzed, and the most promising ones were selected for the operating range of a magnetocaloric device (290–296 K). The highest achieved magnetocaloric thermal rectification ratio under transient conditions was up to 295-times higher than with quasi-steady-state operation. This shows that transient operation should be considered for future progress with this technology.
Highlights
Caloric refrigeration is seen as one of the promising alternatives to vapor-compression refrigeration technology1–3
Since the idea was to find the simplest composition of a thermal diode (TD) that shows a satisfactory R, we started with the composition of the materials A1-B1 (TD1) and A2-B2 (TD2), where A1 and A2 had constant thermal conductivities and B1 and B2 were temperature dependent
A numerical 1D model based on the finite-difference method and Fourier’s heat-conduction law was used to analyze various TDs in a magnetocaloric device
Summary
Caloric refrigeration is seen as one of the promising alternatives to vapor-compression refrigeration technology. Caloric refrigeration is seen as one of the promising alternatives to vapor-compression refrigeration technology1–3 This technology is based on exploiting the so-called caloric effect, where the temperature of a caloric material changes with a changing external parameter: i) magnetic field for a magnetocaloric material; ii) electric field for an electrocaloric material8–. ; iii) applied stress for an elastocaloric material; iv) applied pressure for a barocaloric material or; v) a combination of some or all of them for a multicaloric material under adiabatic conditions. Application of the external field under adiabatic conditions, which leads to an increase in the temperature of the caloric material. Heat transfer from the caloric material to the heat sink while the external field is being applied
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