Heat Transfer by Simultaneous Conduction and Radiation in an Absorbing Medium

Heat transfer by simultaneous conduction and radiation in a thermal radiation absorbing and emitting medium is considered. Consideration is given to a one-dimensional system consisting of two, diffuse, nonblack, infinite, isothermal, parallel plates separated by a finite distance. The space between the plates is filled with a thermal radiation absorbing and emitting medium. The problem is formulated in terms of a nonlinear integro-differential equation and the solution is obtained by reducing it to a nonlinear integral equation. The numerical results are obtained by an iterative method. The temperature distributions and heat transfer are calculated. Two approximate methods for formulating radiant heat-transfer problems are presented and comparisons of the results are made with the most exact solution.

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Heat Transfer by Conduction and Radiation in Absorbing and Scattering Materials

Journal of Heat Transfer ◽

10.1115/1.3689035 ◽

1965 ◽

Vol 87 (1) ◽

pp. 143-150 ◽

Cited By ~ 73

Author(s):

R. Viskanta

Keyword(s):

Heat Transfer ◽

Radiant Energy ◽

Dimensional System ◽

Parallel Plates ◽

Heat Transfer Characteristics ◽

One Dimensional ◽

System Parameters ◽

Finite Distance ◽

Radiant Energy Transfer ◽

Scattering Material

Heat transfer by simultaneous conduction and radiation in thermal radiation absorbing, emitting, and scattering materials is investigated theoretically. Consideration is given to a one-dimensional system consisting of two diffuse, nonblack, isothermal parallel plates separated by a finite distance. The space between the two plates is filled with an isotropically scattering material. The problem is formulated exactly in terms of integrodifferential and integral equations. The results define as well as illustrate several mechanisms of radiant energy transfer and show how one mode of heat transfer influences the other. The numerical results reveal the effect of the system parameters on the heat transfer characteristics. In particular, it is shown that the effect of albedo on the heat transfer is small. Albedo being the parameter which represents the fraction of the incident pencil of radiation which has been scattered.

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Radiant Heat Transfer From Isothermal Dispersions With Isotropic Scattering

Journal of Heat Transfer ◽

10.1115/1.3614389 ◽

1967 ◽

Vol 89 (4) ◽

pp. 300-308 ◽

Cited By ~ 20

Author(s):

R. H. Edwards ◽

R. P. Bobco

Keyword(s):

Heat Transfer ◽

Approximate Solutions ◽

Radiant Heat ◽

Second Order ◽

Isotropic Scattering ◽

Radiant Heat Transfer ◽

Approximate Methods ◽

First Order ◽

Order Solution ◽

Radiant Transfer

Two approximate methods are presented for making radiant heat-transfer computations from gray, isothermal dispersions which absorb, emit, and scatter isotropically. The integrodifferential equation of radiant transfer is solved using moment techniques to obtain a first-order solution. A second-order solution is found by iteration. The approximate solutions are compared to exact solutions found in the literature of astrophysics for the case of a plane-parallel geometry. The exact and approximate solutions are both expressed in terms of directional and hemispherical emissivities at a boundary. The comparison for a slab, which is neither optically thin nor thick (τ = 1), indicates that the second-order solution is accurate to within 10 percent for both directional and hemispherical properties. These results suggest that relatively simple techniques may be used to make design computations for more complex geometries and boundary conditions.

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