Topic
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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TL;DR: In this paper, the boundary layer flow of Eyring Powell nanofluid past a constantly moving surface under the influence of nonlinear thermal radiation was analyzed and the effects of variable thermal conductivity and chemical reaction were also considered.
Abstract: Present analysis discusses the boundary layer flow of Eyring Powell nanofluid past a constantly moving surface under the influence of nonlinear thermal radiation. Heat and mass transfer mechanisms are examined under the physically suitable convective boundary condition. Effects of variable thermal conductivity and chemical reaction are also considered. Series solutions of all involved distributions using Homotopy Analysis method (HAM) are obtained. Impacts of dominating embedded flow parameters are discussed through graphical illustrations. It is observed that thermal radiation parameter shows increasing tendency in relation to temperature profile. However, chemical reaction parameter exhibits decreasing behavior versus concentration distribution.
51 citations
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TL;DR: In this paper, a fluctuational electrodynamics-based formalism for calculating near-field radiative heat transfer between objects of arbitrary size and shape and an infinite surface is presented.
Abstract: A fluctuational electrodynamics-based formalism for calculating near-field radiative heat transfer between objects of arbitrary size and shape and an infinite surface is presented. The surface interactions are treated analytically via Sommerfeld's theory of electric dipole radiation above an infinite plane. The volume integral equation for the electric field is discretized using the thermal discrete dipole approximation (T-DDA). The framework is verified against exact results in the sphere-surface configuration and is applied to analyze near-field radiative heat transfer between a complex-shaped probe and an infinite plane, both made of silica. It is found that, when the probe tip size is approximately equal to or smaller than the gap $d$ separating the probe and the surface, coupled localized surface phonon (LSPh)-surface phonon-polariton (SPhP) mediated heat transfer occurs. In this regime, the net spectral heat rate exhibits four resonant modes due to LSPhs along the minor axis of the probe, while the net total heat rate in the near field follows a ${d}^{\ensuremath{-}0.3}$ power law. Conversely, when the probe tip size is much larger than the separation gap $d$, heat transfer is mediated by SPhPs, resulting in two resonant modes in the net spectral heat rate, corresponding to those of a single emitting silica surface, while the net total heat rate approaches a ${d}^{\ensuremath{-}2}$ power law. It is also demonstrated that a complex-shaped probe can be approximated by a prolate spheroidal electric dipole when the thermal wavelength is larger than the major axis of the spheroidal dipole and when the separation gap $d$ is much larger than the radius of curvature of the dipole tip facing the surface.
51 citations
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TL;DR: In this paper, a high-speed video camera and a thermal infrared imaging device were used to record the flame propagation process and the thermal-radiation effects of the fireball at the combustion-tube outlet.
Abstract: To reveal the flame-propagation behavior and the thermal-radiation effects during coal-dust explosions, two coal-dust clouds were tested in a semi-enclosed vertical combustion tube. A high-speed video camera and a thermal infrared imaging device were used to record the flame-propagation process and the thermal-radiation effects of the fireball at the combustion-tube outlet. The flame propagated more quickly and with a higher temperature in the more volatile coal-dust cloud. The coal-dust concentration also significantly affected the propagation behavior of the combustion zone. When the coal-dust concentration was increased, the flame-propagation velocity and the fireball temperature increased before decreasing overall. Based on the experimental results, a dynamic model of the thermal radiation was employed to describe the changes in the fireballs quantitatively and to estimate the thermal-radiation effects during coal-dust explosions.
51 citations
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20 Oct 1993
TL;DR: In this article, a temperature-controlled laser sintering system includes a laser beam 12 which is focussed onto a Sintering bed 38 by a focussing mirror 26 and a set of scanning mirrors 32,34.
Abstract: A temperature-controlled laser sintering system includes a laser beam 12 which is focussed onto a sintering bed 38 by a focussing mirror 26 and a set of scanning mirrors 32,34. Thermal radiation 114 emitted from the sintering bed 38 are imaged to the scanning mirrors and to a dichroic beamsplitter 110 which reflects such radiation but passes the wavelength of the laser beam 12. The radiation 118 is focussed onto an optical detector 126 which provides a signal on a line 128 to a power control circuit 104. The power control circuit 104 controls a modulator 100 which modulates the power of the laser beam 112 so as to maintain the thermal radiation emission 114 (and thus the temperature at the sintering location) at a substantially constant level.
51 citations