Heat Transfer by Conduction and Radiation in Absorbing and Scattering Materials

1965 ◽  
Vol 87 (1) ◽  
pp. 143-150 ◽  
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.

Heat Transfer by Simultaneous Conduction and Radiation in an Absorbing Medium

1962 ◽  
Vol 84 (1) ◽  
pp. 63-72 ◽  
Author(s):  
R. Viskanta ◽  
R. J. Grosh
Keyword(s):  
Heat Transfer ◽  
Thermal Radiation ◽  
Radiant Heat ◽  
Radiant Heat Transfer ◽  
Dimensional System ◽  
Parallel Plates ◽  
Approximate Methods ◽  
One Dimensional ◽  
Finite Distance ◽  
Transfer Problems

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.

Interaction of Heat Transfer by Conduction, Convection, and Radiation in a Radiating Fluid

1963 ◽  
Vol 85 (4) ◽  
pp. 318-328 ◽  
Author(s):  
R. Viskanta
Keyword(s):  
Heat Transfer ◽  
Energy Transport ◽  
Relative Role ◽  
Heat Transfer Characteristics ◽  
Temperature Variations ◽  
System Parameters ◽  
Heating And Cooling ◽  
Finite Distance ◽  
Parallel Surfaces

Consideration is given to the interaction of conduction, convection, and radiation in a fully developed laminar flow. The flat duct consists of two diffuse, nonblack, isothermal parallel surfaces a finite distance apart; the fluid between them emits and absorbs thermal radiation. The problem is formulated in terms of a nonlinear integro-differential equation, and the solution is obtained by a method employed by Barbier. Numerical examples show the influence of the system parameters such as the optical thicknesses, the ratio which determines the relative role of energy transport by conduction to that by radiation, the emissivity of the duct walls as well as the differences between heating and cooling on the temperature variations across the duct and on the heat-transfer characteristics. Two methods for obtaining approximate temperature distributions for optically transparent and opaque radiating media are outlined and the results discussed.

Heat Transfer by Conduction and Radiation in a One-Dimensional Absorbing, Emitting and Anisotropically-Scattering Medium

1980 ◽  
Vol 102 (2) ◽  
pp. 303-307 ◽  
Author(s):  
W. W. Yuen ◽  
L. W. Wong
Keyword(s):  
Heat Transfer ◽  
Anisotropic Scattering ◽  
Total Heat ◽  
Approximation Technique ◽  
Dimensional System ◽  
General Effect ◽  
Total Heat Transfer ◽  
One Dimensional ◽  
The Common ◽  
Scattering Material

Heat transfer by simultaneous conduction and radiation in an absorbing, emitting and anisotropically-scattering material is investigated theoretically. Consideration is given to a one-dimensional system bounded by two parallel gray, diffuse and isothermal walls. Assuming a physical model of linear-anisotropic scattering, the resulting integral-differential equation is solved by a successive approximation technique similar to the method of undetermined parameters. The solution method is demonstrated to be relatively simple and yields solution converging qucikly to the exact results. Results show that for the present one-dimensional system, the common approach of treating the total heat transfer as a simple addition of separate independent contributions from conduction and radiation is quite inaccurate for certain cases. This approach is thus ineffective in illustrating the general effect of scattering. Both the scattering albedo and the forward-backward scattering parameters are shown to have some interesting effects on the total heat transfer and the medium’s temperature. The magnitude of these effects depends on the surface emissivity of the two boundaries.

Numerical Study on Heat Transfer Characteristics From Parallel Plates With Cavities Swept by a Visco-Elastic Fluid

2010 ◽  
Author(s):  
Hiroshi Suzuki ◽  
Shinpei Maeda ◽  
Yoshiyuki Komoda
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Thermal Field ◽  
Numerical Study ◽  
Geometric Parameters ◽  
Two Dimensional ◽  
Parallel Plates ◽  
Heat Transfer Characteristics ◽  
Elastic Fluid ◽  
Heat Transfer Augmentation

Two-dimensional numerical computations have been performed in order to investigate the development characteristics of flow and thermal field in a flow between parallel plates swept by a visco-elastic fluid. In the present study, the effect of the cavity number in the domain and of Reynolds number was focused on when the geometric parameters were set constant. From the results, it is found that the flow penetration into the cavities effectively causes the heat transfer augmentation in the cavities in any cavity region compared with that of water case. It is also found that the development of thermal field in cases of the present visco-elastic fluid is quicker compared with that of water cases. The present heat transfer augmentation technique using Barus effect of a visco-elastic fluid is effective in the range of low Reynolds number.

Numerical Investigation of Heat Transfer Characteristics of Debris Bed After Severe Accident of SFR Based on 1-D Heat Conduction Model

2018 ◽  
Author(s):  
Mengwei Zhang ◽  
Bin Zhang ◽  
Jianqiang Shan
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Transfer Process ◽  
Severe Accident ◽  
Heat Transfer Characteristics ◽  
Conduction Model ◽  
One Dimensional ◽  
The Core ◽  
Transfer Characteristics ◽  
Core Catcher

Nuclear reactor severe accidents can lead to the release of a large amount of radioactive material and cause immense disaster to the environment. Since the Fukushima nuclear accident in Japan, the severe accident research has drawn worldwide attention. Based on the one-dimensional heat conduction model, a DEBRIS-HT program for analyzing the heat transfer characteristics of a debris bed after a severe accident of a sodium-cooled fast reactor was developed. The basic idea of the DEBRIS-HT program is to simplify the complex energy transfer process in the debris bed to a simple one-dimensional heat transfer problem by solving the equivalent thermal conductivity in different situations. In this paper, the DEBRIS-HT program code is prepared by using the existing model and compared with the experimental results. The results show that the DEBRIS-HT program can correctly predict the heat transfer process in the fragment bed. In addition, the heat transfer characteristics analysis program is also used to model the core catcher of the China fast reactor. Firstly, the dryout heat flux when all of molten core dropped on the core catcher was calculated, which was compared with the result of Lipinski’s zero dimensional model, and the error between two values is only 11.2%. Then, the temperature distribution was calculated with the heat power of 15MW.

scholarly journals Investigation of the compatibility between one-dimensional system parameters and the multidimensional solvation parameter model in RP liquid column chromatography

2003 ◽  
Vol 68 (7) ◽  
pp. 565-579
Author(s):  
Tomislav Janjic ◽  
Gordana Vuckovic ◽  
Milenko Celap
Keyword(s):  
Phase Equilibrium ◽  
Equilibrium Constant ◽  
Column Chromatography ◽  
Dimensional System ◽  
Solvation Parameter Model ◽  
Chromatographic System ◽  
One Dimensional ◽  
System Parameters ◽  
Liquid Column Chromatography ◽  
Solvation Parameter

It has been established that in many cases the system constants used in the Solvation parameter model as well as the corresponding log k values can be linearized in the same NSP and NSP?scale, respectively, which shows the compatibility of both models. NSP and NSP?are one-dimensional system parameters adapted to the chromatographic system used over the phase equilibrium constant.

Heat Transfer Characteristics of Porous Radiant Burners

1991 ◽  
Vol 113 (2) ◽  
pp. 423-428 ◽  
Author(s):  
T. W. Tong ◽  
S. B. Sathe
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Heat Generation ◽  
Numerical Study ◽  
Radiant Energy ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
High Heat Transfer ◽  
Energy Equations ◽  
Radiant Burners

This paper reports a numerical study of the heat transfer characteristics of porous radiant burners, which have significant advantages over conventional burners. The heat transfer characteristics are investigated using a one-dimensional conduction, convection, and radiation model. The combustion phenomenon is modeled as spatially dependent heat generation. Nonlocal thermal equilibrium between the gas and solid phases is accounted for by using separate energy equations for the two phases. The solid matrix is assumed to emit, absorb, and scatter radiant energy. The spherical harmonics approximation is used to solve the radiative transfer equation. The coupled energy equations and the radiative transfer equations are solved using a numerical iterative procedure. The effects of the various factors on the performance of porous radiant burners are determined. It is revealed that for a given rate of heat generation, large optical thicknesses and high heat transfer coefficients between the solid and gas phases are desirable for maximizing radiant output. Also, low solid thermal conductivities, scattering albedos and flow velocities, and high inlet environment reflectivities produced high radiant output.

Thermal and Stability Analysis of Formed Platelet in Platelet Transpiration Cooling

2011 ◽  
Vol 52-54 ◽  
pp. 859-864 ◽  
Author(s):  
Yong Fa Hou ◽  
Wei Qiang Liu
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Critical Thickness ◽  
Heated Wall ◽  
Transpiration Cooling ◽  
Heat Transfer Characteristics ◽  
One Dimensional ◽  
Reusable Launch Vehicle ◽  
The Stability ◽  
Key Techniques

Platelet transpiration cooling is one of the key techniques for the developing reusable launch vehicle. The thinner of the platelet, the better effect plate transpiration will gain. Meanwhile, the platelet unit may get wrinkled if thermal stress is large enough. One-dimensional non-equilibrium model is adopted to analyze the heat transfer characteristics of platelet transpiration cooling. The assumption of rectangular plate with three-side simple supported and one-side free is taken and Galerkin method is applied for analyzing the stability of platelet unit. Analysis indicates that as the heat transfer intensity increases, the thermal soaking depth decreases, while more coolant is needed to keep the heated wall at design temperature. Also, the critical thickness for the platelet not to get wrinkled gets larger with the increasing thermal soaking depth.

Differential Approximation of Radiative Heat Transfer in a Gray Medium: Axially Symmetric Radiation Field

1980 ◽  
Vol 102 (4) ◽  
pp. 719-723 ◽  
Author(s):  
J. Higenyi ◽  
Y. Bayazitogˇlu
Keyword(s):  
Heat Transfer ◽  
Radiation Field ◽  
Radiative Heat ◽  
Numerical Solutions ◽  
Radiant Energy ◽  
Axially Symmetric ◽  
Differential Approximation ◽  
Emissive Power ◽  
One Dimensional ◽  
Gray Medium

The differential approximation is used to analyze an axially symmetric radiation field for a gray medium within a finite, cylindrical enclosure. The medium emits, absorbs, and isotropically scatters radiant energy and is subject to a specified heat generation. Numerical solutions are obtained for the radiative heat flux and emissive power distributions. It is found that the accuracy of the differential approximation is of the same order for the axially symmetric and one-dimensional problems.

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