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Thermal radiation

About: Thermal radiation is a research topic. Over the lifetime, 12290 publications have been published within this topic receiving 197186 citations. The topic is also known as: heat radiation.


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Journal ArticleDOI
TL;DR: In this paper, a simple and general procedure for calculating the thermal radiation coming from any stationary metric is presented, where the radiation arises as the quasi-classical tunneling of particles through a gravitational barrier.
Abstract: We present a simple and general procedure for calculating the thermal radiation coming from any stationary metric. The physical picture is that the radiation arises as the quasi--classical tunneling of particles through a gravitational barrier. We show that our procedure can reproduce the results of Hawking and Unruh radiation. We also show that under certain kinds of coordinate transformations the temperature of the thermal radiation will change in the case of the Schwarzschild black holes. In addition we apply our procedure to a rotating/orbiting system and show that in this case there is no radiation, which has experimental implications for the polarization of particles in circular accelerators.

149 citations

Journal ArticleDOI
TL;DR: This work measures radiative heat transfer for large temperature differences using a custom-fabricated device in which the gap separating two 5 × 5 mm2 intrinsic silicon planar surfaces is modulated from 3,500 to 150 nm and paves the way for the establishment of novel evanescent wave-based systems.
Abstract: Using Rytov’s fluctuational electrodynamics framework, Polder and Van Hove predicted that radiative heat transfer between planar surfaces separated by a vacuum gap smaller than the thermal wavelength exceeds the blackbody limit due to tunnelling of evanescent modes. This finding has led to the conceptualization of systems capitalizing on evanescent modes such as thermophotovoltaic converters and thermal rectifiers. Their development is, however, limited by the lack of devices enabling radiative transfer between macroscale planar surfaces separated by a nanosize vacuum gap. Here we measure radiative heat transfer for large temperature differences (∼120 K) using a custom-fabricated device in which the gap separating two 5 × 5 mm2 intrinsic silicon planar surfaces is modulated from 3,500 to 150 nm. A substantial enhancement over the blackbody limit by a factor of 8.4 is reported for a 150-nm-thick gap. Our device paves the way for the establishment of novel evanescent wave-based systems. Evanescent coupling between surfaces separated by a distance smaller than the thermal wavelength can lead to radiative heat transfer greater than the blackbody limit. Here, the authors demonstrate this between two macroscopic-scale surfaces, paving the way to harnessing the effect in thermal devices.

148 citations

Journal ArticleDOI
TL;DR: A platform for near-field heat transfer on-chip is demonstrated and it is shown that it can be the dominant thermal transport mechanism between integrated nanostructures, overcoming background substrate conduction and the far-field limit.
Abstract: Near-field heat transfer recently attracted growing interest but was demonstrated experimentally only in macroscopic systems. However, several projected applications would be relevant mostly in integrated nanostructures. Here we demonstrate a platform for near-field heat transfer on-chip and show that it can be the dominant thermal transport mechanism between integrated nanostructures, overcoming background substrate conduction and the far-field limit (by factors 8 and 7, respectively). Our approach could enable the development of active thermal control devices such as thermal rectifiers and transistors.

148 citations

Journal ArticleDOI
TL;DR: In this article, the authors simulate the interaction between thermal surface radiation and nanofluid free convection in a two dimensional shallow cavity by lattice Boltzmann method, and the results are presented as the profiles of velocity and temperature and also the streamlines and isotherms.
Abstract: This paper aims to simulate the interaction between thermal surface radiation and nanofluid free convection in a two dimensional shallow cavity by lattice Boltzmann method. The supposed nanofluid is generated by a homogeneous mixture of water and nanoparticles of Al2O3. The upper and lower walls of cavity are maintained at cold and hot temperature, respectively; while the side walls are kept thermally insulated. The cavity aspect ratio is chosen as 5 which indicates a shallow one. The cavity all inner surfaces are considered as the gray diffuse emitters and reflectors of radiation. The computations are performed for the wide range of parameters as Ra = 104 and Ra = 105; e = 0 . 5 and e = 0 . 9 while nanoparticles volume fraction changes between 0.0 ≤ φ ≤ 0.04 at each case. As a result, the effects of emissivity and Rayleigh number are studied on the total heat transfer of radiation and free convection of nanofluid. The suitable validations are examined beside the useful grid study procedure. The results are presented as the profiles of velocity and temperature and also the streamlines and isotherms. Moreover the local and averaged Nusselt numbers are provided for the coupled and uncoupled states of radiation and free convection heat transfer mechanisms. It is seen that Nu m of total free convection and radiation would be more at higher Ra and e ; which indicates that radiation heat transfer coupled with free convection might affect the flow field and improve the Nusselt number.

148 citations

Journal ArticleDOI
TL;DR: In this paper, a coherent thermal source was constructed with a thin polar material coated on a one-dimensional photonic crystal, and the excitation of surface waves at the interface of the coated layer and the photonic lattice resulted in highly spectral and directional emission in the infrared for both the transverse electric wave and transverse magnetic wave.
Abstract: Coherent thermal emission from surface relief gratings holds promise for spectral and directional control of thermal radiation but is limited to transverse magnetic waves, which can excite surface plasmon or phonon polaritons in the grating structure. We show in this letter that a coherent thermal source can be constructed with a thin polar material coated on a one-dimensional photonic crystal. The excitation of surface waves at the interface of the coated layer and the photonic crystal results in highly spectral and directional emission in the infrared for both the transverse electric wave and the transverse magnetic wave.

148 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023375
2022749
2021575
2020636
2019663
2018618