Heat management and losses of electrocaloric cooling devices based on electrostatic thermal switches

Depreux, Lucas; Almanza, Morgan; Zeggai, N.; Parrain, Fabien; Lobue, Martino

doi:10.1016/j.applthermaleng.2022.118290

Cited by 4 publications

(2 citation statements)

References 14 publications

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“…about 20% of the losses of the square profile at the same field and frequency). This confirms the relevance, in order to properly estimate the caloric performance of a material, of carrying measurements under excitation waveforms change, viscous losses associated with the moving parts [22] etc.) are neglected.…”

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confidence: 70%

Cooling efficiency and losses in electrocaloric materials

Zeggai

Dkhil

Lobue

et al. 2023

Applied Physics Letters

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A figure of merit for assessing the cooling efficiency of electrocaloric (EC) materials is defined, where the caloric properties are taken into account jointly with the material's losses. Using a specifically developed measurement setup, based on flexible thermistances, the caloric effect and the losses are directly measured on P(VDF-TrFE-CFE) electrocaloric polymer films. The data are used, jointly with our figure of merit, to extrapolate the cooling efficiency to be expected, under actual working conditions, from the studied EC material. Dielectric losses emerge as a major limiting factor for achieving the needed cooling performance. This finding shows that, beside the research for huge caloric response, material loss reduction has to be considered a key objective for researching an optimal EC refrigerant for cooling applications. Eventually, some strategies toward loss reduction are outlined.

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confidence: 70%

Cooling efficiency and losses in electrocaloric materials

Zeggai

Dkhil

Lobue

et al. 2023

Applied Physics Letters

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“…In the last two decades, intensive studies have been conducted on different types of macroscopic, mechanical and MEMS thermal switches [1][2][3][4], which also includes their integration in caloric (ferroic) technologies [5]. By focusing on the last 5 years, and considering (micro)mechanical thermal switches and their applications in cooling, heating or thermal energy harvesting using ferroic materials, the majority of research activities were performed in the field of electrocalorics [6][7][8][9][10][11][12][13][14][15][16][17][18][19] or pyroelectrics [20][21][22][23][24]. A much smaller number of publications can be found for the domains of magnetocalorics [17,[25][26][27] and pyromagnetics (thermomagnetics) [28][29][30][31][32][33][34] or elastocalorics [35][36][37].…”

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confidence: 99%

A conceptual design of a thermal switch capacitor in a magnetocaloric device: experimental characterization of properties and simulations of operating characteristics

2023

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The quest for better performance from magnetocaloric devices has led to the development of thermal control devices, such as thermal switches, thermal diodes, and thermal capacitors. These devices are capable of controlling the intensity and direction of the heat flowing between the magnetocaloric material and the heat source or heat sink, and therefore have the potential to simultaneously improve the power density and energy efficiency of magnetocaloric systems. We have developed a new type of thermal control device, i.e., a silicon mechanical thermal switch capacitor. In this paper we first review recently developed thermal switches based on MEMS and present the operation and structure of our new thermal switch capacitor. Then, the results of the parametric experimental study on the thermal contact resistance, as one of the most important parameters affecting the thermal performance of the device, are presented. These experimental data were later used in a numerical model for a magnetocaloric device with a thermal switch-capacitor. The results of the study show that for a single embodiment, a maximum cooling power density of 970 W/m2 (510 W/kgmcm) could be achieved for a zero-temperature span and an operating frequency of 5 Hz. However, a larger temperature span could be achieved by cascading multiple magnetocaloric elements with thermal switch capacitors. We have shown that the compact thermal switch capacitor can be used in caloric devices, even with small temperature variations, and can be used in a variety of practical applications requiring thermal regulation.

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