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 article, a mathematical heat transfer model for the prediction of heat flux on the slab surface and temperature distribution in the slab has been developed by considering the thermal radiation in the furnace chamber and transient heat conduction governing equations in the slabs, respectively.
120 citations
TL;DR: In this paper, an upper limit for the electrical energy current to the absorbed heat current was derived as a function of the value of the bandgap of the semiconductor, assuming that the absorptivity of the electron-hole system of a semiconductor is unity for photon energies larger than the band gap.
Abstract: A semiconductor in the solar radiation field acts as a thermal electronic engine. It converts absorbed radiation heat into chemical energy of the excited electron-hole gas. In flow equilibrium, a homogeneous semiconductor gives off this chemical energy by radiative recombination to the surroundings. If provision is made, as by a p-n junction, to divert the excited electrons and holes, before they recombine, from their point of generation, their chemical energy may be converted into electrical energy. The ratio of this chemical energy current, which constitutes an upper limit for the obtainable electrical energy current, to the absorbed heat current is computed as a function of the value of the bandgap of the semiconductor. Under the assumption that the absorptivity of the electron-hole system of the semiconductor is unity for photon energies larger than the bandgap and zero for smaller photon energies, the conversion efficiency for unfocussed sunlight has a maximum of 30 percent for a bandgap of 1:3 eV.
119 citations
TL;DR: In this article, an attempt is made to study nonlinear radiation and chemical reactive magnetohydrodynamic (MHD) flow of nanofluid, which comprises water and copper (Cu) and silver (Ag) as nanoparticles.
Abstract: An attempt is accomplished to study nonlinear radiation and chemical reactive magnetohydrodynamic (MHD) flow of nanofluid. Nanofluid comprises water and copper (Cu) and silver (Ag) as nanoparticles. Effect of porous medium is also taken into account. Characteristics of heat and mass transfers are discussed via homogeneous-heterogeneous reactions. Correlation behavior of surface drag force and heat transfer rate is discussed. Probable error and statistical declaration for drag force and heat transfer rate are computed. Ordinary differential systems have been considered. Solutions of the problem are presented via a numerical technique namely Euler’s Explicit Method (EEM). The key roles of different embedded parameters on different characteristics of fluid are discussed graphically. The outcomes of the given problem demonstrate that non-linear radiation has noteworthy effect on both temperature and heat transfer coefficient.
119 citations
TL;DR: In this article, the authors exploit the coupling of adjacent phonon-polaritonic nanostructures, demonstrating experimentally that the nanometer-scale gaps can control the thermal emission frequency while retaining emission line widths as narrow as 10 cm-1.
Abstract: A conventional thermal emitter exhibits a broad emission spectrum with a peak wavelength depending upon the operation temperature. Recently, narrowband thermal emission was realized with periodic gratings or single microstructures of polar crystals supporting distinct optical modes. Here, we exploit the coupling of adjacent phonon-polaritonic nanostructures, demonstrating experimentally that the nanometer-scale gaps can control the thermal emission frequency while retaining emission line widths as narrow as 10 cm–1. This was achieved by using deeply subdiffractional bowtie-shaped silicon carbide nanoantennas. Infrared far-field reflectance spectroscopy, near-field optical nanoimaging, and full-wave electromagnetic simulations were employed to prove that the thermal emission originates from strongly localized surface phonon-polariton resonances of nanoantenna structures. The observed narrow emission line widths and exceptionally small modal volumes provide new opportunities for the user-design of near- and...
119 citations
TL;DR: In this article, the authors extended the classical problem of the motion of a one-dimensional unsteady shock generated by a piston moving with velocity vp = ctn to take into account thermal radiation effects.
Abstract: The classical problem of the motion of a one-dimensional unsteady shock generated by a piston moving with velocity vp = ctn is extended to take into account thermal radiation effects by the similarity method of Taylor and Sedov. Gray gas and local thermodynamic equilibrium are assumed and a modification of the Schuster-Schwarzschild differential equation for the heat flux is adopted. The optical thickness is not restricted to be thin or thick, and the absorption coefficient is assumed to vary with the density and temperature. Numerical results indicate that the pressure and velocity are not affected much by the radiation, but the density, temperature and radiant heat flux are changed considerably.
118 citations