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.

Radiative heat transfer through opacified fibers and powders

Abstract: Radiative heat transfer through opacified (metallic or metallized) cylindrical fibers and spherical powders is investigated theoretically. The radiative properties of these packed particles are evaluated by using the solutions of electromagnetic theory. The large optical constants and large particle size parameters require an improved numerical scheme for evaluation of these properties. The results show that fine metal fibers provide excellent thermal radiation resistance. For the packed spheres, the high solid volume fraction restricts the present model to the geometric scattering regime. The results in this regime indicate better radiation resistance for smaller spheres. It is also interesting to note that, relative to unopacified spheres, the opacified spheres have higher thermal radiation resistance only at high temperatures.

Multiple Slip Effects on Magnetohydrodynamic Axisymmetric Buoyant Nanofluid Flow above a Stretching Sheet with Radiation and Chemical Reaction

Abstract: The present article investigates the effect of multiple slips on axisymmetric magnetohydrodynamics (MHD) buoyant nano-fluid flow over a stretching sheet with radiation and chemical effect. The non-linear partial differential equations were transformed to a non-linear control equation using an appropriate similarity transformation. The governing equations were solved through the finite element method. The influence of physical parameters such as multiple slips, magnetic, thermal radiation, Prandtl number, stretching, Brownian motion, thermophoresis, Schmidt number, Lewis number and chemical reaction on the radial velocity, temperature, solutal concentration and nano-fluid volume fraction profile were investigated. We noted that the boundary layers increases in the presence of multiple slip effects whereas, the effect of thermal slip on Nusselt number increases with the increasing values of magnetic and thermal radiation. To verify the convergence of the numerical solution, the computations were made by reducing the mesh size. Finally, our results are parallel to previous scholarly contributions.

Thermal Radiation in the Upper Atmosphere

Abstract: Atmospheric radiation calculations usually assume a Boltzmann distribution of molecules among the vibrational and rotational energy levels. At the low pressures encountered high in the earth's atmosphere, the collision rate is insufficient to maintain such a distribution. An equation of transfer is derived, for a vibration-rotation band, which does not assume a Boltzmann distribution among the vibrational levels. From this is derived an equation for the heating rate due to the band in a plane-stratified atmosphere. It is shown that the heating rate per unit mass tends to zero with the pressure, because of the departure from a Boltzmann distribution, which becomes serious above about 75 km. A method of solving the equation for the heating rate is described, and is applied to a model of the 15 $\mu $ carbon dioxide band as an example. The effect of departures from a Boltzmann distribution among the rotational levels is also considered, and it is shown to be unimportant for vibration-rotation bands, but to limit computations on the water-vapour rotation band to heights less than about 90 km.