A concept of heat dissipation coefficient for thermal cloak based on entropy generation approach

Xu, Guoqiang; Zhang, Haochun

doi:10.1063/1.4962922

Cited by 10 publications

(2 citation statements)

References 32 publications

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“…In order to investigate the thermodynamic performances of the metamaterial tunable cell, entropy generation analysis [18,19,24,44,45] is introduced to define the thermal dissipations of different schemes with varying rotations and selected materials. The volumetric local entropy generation rate for such systems in a transformed 2D domain [19,24,44,45] can be observed using the Fourier transform:…”

Section: Rotation Of Heat Flux Based On Transformation Opticsmentioning

confidence: 99%

Investigating the Thermodynamic Performances of TO-Based Metamaterial Tunable Cells with an Entropy Generation Approach

Zhang

et al. 2017

Entropy

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Active control of heat flux can be realized with transformation optics (TO) thermal metamaterials. Recently, a new class of metamaterial tunable cells has been proposed, aiming to significantly reduce the difficulty of fabrication and to flexibly switch functions by employing several cells assembled on related positions following the TO design. However, owing to the integration and rotation of materials in tunable cells, they might lead to extra thermal losses as compared with the previous continuum design. This paper focuses on investigating the thermodynamic properties of tunable cells under related design parameters. The universal expression for the local entropy generation rate in such metamaterial systems is obtained considering the influence of rotation. A series of contrast schemes are established to describe the thermodynamic process and thermal energy distributions from the viewpoint of entropy analysis. Moreover, effects of design parameters on thermal dissipations and system irreversibility are investigated. In conclusion, more thermal dissipations and stronger thermodynamic processes occur in a system with larger conductivity ratios and rotation angles. This paper presents a detailed description of the thermodynamic properties of metamaterial tunable cells and provides reference for selecting appropriate design parameters on related positions to fabricate more efficient and energy-economical switchable TO devices.

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Section: Rotation Of Heat Flux Based On Transformation Opticsmentioning

confidence: 99%

Investigating the Thermodynamic Performances of TO-Based Metamaterial Tunable Cells with an Entropy Generation Approach

Zhang

et al. 2017

Entropy

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“…The form invariance of the heat diffusion equation after coordinate transformation led to the extension of TO to the thermal field to guide the design and experiments of thermal TO devices including thermal cloaks, [7][8][9][10][11][12][13] concentrators, [14][15][16][17][18][19][20][21][22][23][24][25] rotators, 26 camouflage, 27 and diodes. 28 With thermal TO devices, an active and efficient control of thermal energy can be achieved with a pre-designed profile and reasonable arrangement of metamaterials.…”

Section: Introductionmentioning

confidence: 99%

Geometrical effects on the concentrated behavior of heat flux in metamaterials thermal harvesting devices

Zhang

Xie

et al. 2017

AIP Advances

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Thermal harvesting devices based on transformation optics, which can manipulate the heat flux concentration significantly through rational arrangements of the conductivities, have attracted considerable interest owing to several great potential applications of the technique for high-efficiency thermal conversion and collection. However, quantitative studies on the geometrical effects, particularly wedge angles, on the harvesting behaviors are rare. In this paper, we adopt wedge structure-based thermal harvesting schemes, and focus on the effects of the geometrical parameters including the radii ratios and wedge angles on the harvesting performance. The temperature deformations at the boundaries of the compressional region and temperature gradients for the different schemes with varying design parameters are investigated. Moreover, a concept for temperature stabilization was derived to evaluate the fluctuation in the energy distributions. In addition, the effects of interface thermal resistances have been investigated. Considering the changes in the radii ratios and wedge angles, we proposed a modification of the harvesting efficiency to quantitatively assess the concentration performance, which was verified through random tests and previously fabricated devices. In general, this study indicates that a smaller radii ratio contributes to a better harvesting behavior, but causes larger perturbations in the thermal profiles owing to a larger heat loss. We also find that a smaller wedge angle is beneficial to ensuring a higher concentration efficiency with less energy perturbations. These findings can be used to guide the improvement of a thermal concentrator with a high efficiency in reference to its potential applications as novel heat storage, thermal sensors, solar cells, and thermoelectric devices.

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Effect of Heat Flux Distribution on Entropy Generation and Irreversibility of Lead-Bismuth Eutectic (LBE) Forced Convective Heat Transfer

Zhang

Wang

et al. 2022

J. Therm. Sci.

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A concept of heat dissipation coefficient for thermal cloak based on entropy generation approach

Cited by 10 publications

References 32 publications

Investigating the Thermodynamic Performances of TO-Based Metamaterial Tunable Cells with an Entropy Generation Approach

Investigating the Thermodynamic Performances of TO-Based Metamaterial Tunable Cells with an Entropy Generation Approach

Geometrical effects on the concentrated behavior of heat flux in metamaterials thermal harvesting devices

Effect of Heat Flux Distribution on Entropy Generation and Irreversibility of Lead-Bismuth Eutectic (LBE) Forced Convective Heat Transfer

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