Theory of thermal nonequilibrium entropy in near-field thermal radiation

Narayanaswamy, Arvind; Zheng, Yi

doi:10.1103/physrevb.88.075412

Cited by 17 publications

(24 citation statements)

References 35 publications

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“…By introducing a mean transmission factor, a mesoscopic Landauer-type formula derived in Biehs et al [7] expressed the nanoscale heat transfer coefficient as a product of the universal quantum conductance and the summation of all number of modes weighted by their mean transmission factor. Latella et al [169] performed a thermodynamics analysis of the maximum efficiency using equilibrium entropy and entropy flux, and Narayanaswamy and Zheng [168] formulated a radiation entropy expression for near-field radiation in the vacuum region in the nonequilibrium situation. The consistence and discrepancy between these methods deserve further investigation.…”

Section: Discussionmentioning

confidence: 99%

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Near-Field Thermal Radiation: Recent Progress and Outlook

Liu

Wang

Zhang

2015

Nanoscale and Microscale Thermophysical Engineering

131

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Any materials at temperatures higher than absolute zero emit electromagnetic waves due to the thermal fluctuations of free charges or ions. When two or more bodies at different temperatures are brought sufficiently close to each other with vacuum gap spacing smaller than the characteristic thermal wavelength, near-field radiative heat flux can exceed the far-field blackbody limit, governed by the well-known Stefan-Boltzmann law, by orders of magnitude. This article reviews the recent progress on both theoretical and experimental studies of near-field thermal radiation with an emphasis on its potential applications. Recent theoretical developments are presented, such as near-field radiation of general anisotropic materials and 2D materials, application condition of effective medium theory, and exact numerical methods for dealing with arbitrary particles or periodic nanostructures. Recent experimental achievements are also discussed, focusing on tip-plane and plane-plane configurations with various materials. The wide applications of near-field radiation are summarized in terms of thermal imaging, energy harvesting, and contactless thermal management such as modulation, rectification, and amplification. An outlook is provided on the promise of near-field thermal radiation in energy harvesting, novel thermal sources, and sensing, as well as the development of related fields such as reducing Casimir stiction, minimizing noise current, and increasing spontaneous emission rate. Challenges are also discussed, such as developing exact and fast computational techniques for complex metamaterials, understanding near-field radiation at extreme gap spacing, overcoming weak mode coupling in thermophotovoltaic (TPV) systems, measuring large-area plane-plane configuration at small gap spacing, and realizing devices based on near-field radiation.

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Section: Discussionmentioning

confidence: 99%

“…Recently, a generalized spectral specific intensity was proposed in Narayanaswamy and Zheng [168] to separate the contribution of propagating waves from the evanescent waves in real space. The concept of near-field intensity needs further exploration.…”

Section: Discussionmentioning

confidence: 99%

Near-Field Thermal Radiation: Recent Progress and Outlook

Liu

Wang

Zhang

2015

Nanoscale and Microscale Thermophysical Engineering

131

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“…The dyadic Green's functions in Eq. (8) and those required to evaluate Eq. (10) for a planar multilayered configuration are given by G e (r,r) = G…”

Section: Fluctuational Electrodynamics and Green's Function Formamentioning

confidence: 99%

“…In fact, it is the equilibrium contribution to pressure that dominates over thermal nonequilibrium contribution at small gaps [3]. Both energy and momentum transfer between parallel halfspaces separated by a vacuum gap have been studied by many researchers over the last seven decades [4][5][6][7][8][9]. The expressions for thermal radiative and momentum transfer between two half-spaces (as shown in Fig.…”

Section: Introductionmentioning

confidence: 98%

Patch contribution to near-field radiative energy transfer and van der Waals pressure between two half-spaces

Zheng

Narayanaswamy

2014

Phys. Rev. A

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Near-field effects in fluctuational electrodynamics leads to enhancement of radiative energy transfer as well as the emergence of van der Waals and/or Casimir pressure. While much has been learned from the analysis of near-field interactions between two half-spaces separated by a vacuum gap, we shed new light on the problem by finding how much of a surface patch on one of the half-spaces contributes to the energy transfer or van der Waals pressure at any location within the vacuum gap. We show that energy transfer and fluctuation-induced van der Waals pressure at any point on the surface of one half-space are qualitatively and quantitatively different due to the dissimilar zones of influence of interactions. We also show that the contributions from different surface patches are qualitatively similar for half-spaces with dielectric materials (silica, silicon carbide) and half-spaces with metals (gold).

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“…In particular, fundamental and technological solutions for thermal emission focusing can help to overcome challenges in realizing the near-field coupling schemes. Fundamental studies on the entropy and information content of correlated light fields generated by coherent thermal sources are also important [277][278][279], especially in the processes of light absorption and emission away from thermal equilibrium, when light-matter interactions occur over time scales too short for the thermalization process to take place. This is illustrated by a recent striking demonstration of efficient optical refrigeration via the heat transport between a thermal bath and a non-equilibrium exciton-polariton fluid [280].…”

Section: Advances and Challenges In Fundamental Understanding And Nanmentioning

confidence: 99%

Heat meets light on the nanoscale

et al. 2016

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Abstract:We discuss the state-of-the-art and remaining challenges in the fundamental understanding and technology development for controlling light-matter interactions in nanophotonic environments in and away from thermal equilibrium. The topics covered range from the basics of the thermodynamics of light emission and absorption to applications in solar thermal energy generation, thermophotovoltaics, optical refrigeration, personalized cooling technologies, development of coherent incandescent light sources, and spinoptics.Keywords: thermal emission; absorption; spectral selectivity; angular selectivity; optical refrigeration; solar thermal energy conversion; thermophotovoltaics; nearfield heat transfer; photon density of states; thermal upconversion; radiative cooling Thermodynamics of light and heatControl and optimization of energy conversion processes involving photon absorption and radiation require detailed understanding of thermodynamic properties of radiation as well as its interaction with matter [1-5]. Historically, thermodynamic treatment of electromagnetic radiation began over a century ago with Planck applying the thermodynamic principles established for a gas of material particles to an analogous "photon gas" [1]. In particular, he showed that thermodynamic parameters, such as the energy, volume, temperature, and pressure can be applied to electromagnetic radiation, reflecting the dual wave-particle nature of photons. In this section, we will review the general thermodynamic principles governing photon propagation and interaction with matter, as well

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Theory of thermal nonequilibrium entropy in near-field thermal radiation

Cited by 17 publications

References 35 publications

Near-Field Thermal Radiation: Recent Progress and Outlook

Near-Field Thermal Radiation: Recent Progress and Outlook

Patch contribution to near-field radiative energy transfer and van der Waals pressure between two half-spaces

Heat meets light on the nanoscale

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