METHOD OF EVALUATING SCRIPT F FOR RADIANT EXCHANGE WITHIN AN ENCLOSURE

AIAA Journal ◽  
1963 ◽  
Vol 1 (6) ◽  
pp. 1428-1429 ◽  
Author(s):  
T. ISHIMOTO ◽  
J. T. BEVAN
Keyword(s):  
Radiant Exchange

Improved Monte Carlo Method for Total Radiant Exchange Areas in Cylindrical Enclosure

2021 ◽  
pp. 1-11
Author(s):  
Jiaqi Zhong ◽  
Guojun Li ◽  
Dingyong Li ◽  
Xiaodong Wang ◽  
Cunhai Wang
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Radiant Exchange

Radiative and Convective Conducting Fins on a Plane Wall, Including Mutual Irradiation

1971 ◽  
Vol 93 (1) ◽  
pp. 41-46 ◽  
Author(s):  
R. C. Donovan ◽  
W. M. Rohrer
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Considerable Increase ◽  
Radiative Heat ◽  
Plane Surface ◽  
Heat Fluxes ◽  
Fluid Medium ◽  
Radiant Exchange ◽  
Radiative Component

The radiative and convective heat transfer from a fin array consisting of longitudinal rectangular fins on a plane surface has been theoretically investigated by mathematically describing the interaction among the heat conduction in the fin, the convective heat transfer to the fluid medium, and the radiant exchange of the fin with the neighboring elements. Solutions for the fin temperature distribution, the local radiative heat fluxes over the fin and base surfaces, the total radiative heat transfer, the total convective heat transfer, and the effectiveness of the fins were found. In the primary range of physical interest, the fins usually cause a considerable increase in the convective component of the heat transfer but either cause decreases or only slight increases in the radiative component. Thus convection is generally the more effective mode of heat transfer in fin arrays, and the effectiveness of the fins decreases as the radiative component increases.

Surface Radiation Exchange for Two-Dimensional Rectangular Enclosures Using the Discrete-Ordinates Method

1992 ◽  
Vol 114 (2) ◽  
pp. 465-472 ◽  
Author(s):  
A. Sa`nchez ◽  
T. F. Smith
Keyword(s):  
Weighting Factor ◽  
Heat Fluxes ◽  
Surface Radiation ◽  
Discrete Ordinates ◽  
Two Dimensional ◽  
Discrete Ordinates Method ◽  
Radiation Exchange ◽  
Radiant Exchange ◽  
Irregular Geometries ◽  
Good Agreement

The purpose of this study is to develop a model based on the discrete-ordinates method for computing radiant exchange between surfaces separated by a transparent medium and to formulate the model so that arbitrary arrangements of the surfaces can be accommodated. Heat fluxes from the model are compared to those based on the radiosity/irradiation analysis. Three test geometries that include shadowing and irregular geometries are used to validate the model. Heat fluxes from the model are in good agreement with those from the radiosity/irradiation analysis. Effects of geometries, surface emittances, grid patterns, finite-difference weighting factor, and number of discrete angles are reported.

Reordering the Absorption Coefficient Within the Wide Band for Predicting Gaseous Radiant Exchange

1996 ◽  
Vol 118 (2) ◽  
pp. 394-400 ◽  
Author(s):  
P. Y. C. Lee ◽  
K. G. T. Hollands ◽  
G. D. Raithby
Keyword(s):  
Absorption Coefficient ◽  
Smooth Curve ◽  
Wide Band ◽  
Computational Effort ◽  
Complex Nature ◽  
Smooth Curves ◽  
Exact Answer ◽  
Radiant Exchange ◽  
Vibration Rotation ◽  
Isothermal Gas

The “exact” calculation of the radiant transfer in gaseous enclosures has remained impractical for design; the highly complex nature of the absorption spectrum of the gases has meant that an inordinately large computational effort is required to effect an exact answer. In this paper we show how the complex absorption distribution for an isothermal gas can be replaced by a set of smooth curves. This procedure can be visualized as one of actually reordering the full complex absorption distribution within each vibration-rotation band, and then replacing it by a smooth curve. Such a smooth curve can then be readily approximated by a stepwise function, and radiant exchange calculations can be carried out at each step and then summed over all the steps to get the total exchange. This paper explains how the reordered curve can be obtained and gives some sample plots of the reordered absorption coefficient curve. Fitted functions for the rearranged curves have been provided, and some solutions to the radiant exchange problems are given and compared to line-by-line solutions. About 50 to 200 steps in the stepwise curve are found to be adequate in order to obtain an answer within a few percent of the exact answer.

Radiant exchange in partially specular architectural environments

2003 ◽  
Vol 114 (4) ◽  
pp. 2411-2411
Author(s):  
C. Walter Beamer ◽  
Ralph T. Muehleisen
Keyword(s):  
Radiant Exchange

Analysis of Experimental Simulation of Ground Surface Heating During a Prescribed Burn

1991 ◽  
Vol 1 (2) ◽  
pp. 125 ◽  
Author(s):  
D Pafford ◽  
VK Dhir ◽  
E Anderson ◽  
J Cohen
Keyword(s):  
Surface Temperature ◽  
Flame Temperature ◽  
Ground Surface ◽  
Ambient Air ◽  
Surface Heating ◽  
Experimental Simulation ◽  
Initial Contact ◽  
Prescribed Burn ◽  
Radiant Exchange ◽  
Ash Layer

Ground surface heating during a prescribed bum is modeled. Primarily, the ground surface heating occurs by radiant exchange with the flames. Additional surface heating occurs when hot ash is deposited upon the ground. Heat losses from the ground surface occur by radiant transfer to the sky and surroundings, by conductive transfer of energy into the ground, and by convective transfer to the ambient air. Important flame input characteristics used in the model are: the flame residence time, flame geometry, and flame temperature. Important ash parameters are: inif al ash temperature, location of initial contact of ash with the ground surface, and the thickness of the ash layer. The analysis indicates that in the absence of an ash layer the location of the highest surface temperature is dependent only upon the flame geometry pararneters. However, the magnitude of the ground surface temperature is dependent upon flame geometry, the radiant properties of the flame, and the thermophysical properties of the ground. Results from the model are compared with experimental data. The data were obtained by igniting a prepared fuel bed of chamise and manzanita branches loaded over a table top in which sand filled canisters, instrumented with thermocouples, were set flush with the table surface. The temperature distributions within the sand are found to compare well with the model predictions. Exceptions to the model are found to occur in burns featuring extensive smoldering ember beds.

The basis for a room global temperature

1992 ◽  
Vol 339 (1653) ◽  
pp. 153-191 ◽  
Keyword(s):  
Heat Transfer ◽  
Limited Extent ◽  
Point Temperature ◽  
Heat Flows ◽  
Heating And Cooling ◽  
Radiant Exchange ◽  
Least Squares Fit ◽  
Radiant Temperature ◽  
Building Heat ◽  
Bounding Surfaces

The design of heating and cooling appliances in buildings in routine cases normally proceeds on the assumption of a room index temperature which combines the separate effects of air temperature and of the longwave radiant field m the enclosure. It is pointed out that the basis for the index in current use in the U.K. and elsewhere is flawed, and this article is concerned with the logic of setting up a valid in ex temperature in its place. The argument depends first on reducing the surface-to-surface radiant exchange between enclosure surfaces to an approximately equivalent surface-to-star point exchange, using a least-squares fit. The fit proves to be quite good. It is next established that to a limited extent the star point temperature - a fictitious construct - will do duty for the space-averaged observable radiant temperature in the room. Thirdly, since the index temperature is taken to drive the radiant and convective heat flows from the room as a whole to one of its bounding surfaces, the question is discussed as to how reliably these physically dissimilar mechanisms can be formally merged in this way. Finally, simple expressions are given for enclosure heat needs in relation to comfort temperature and similar quantities. The arguments present some innovative features in building heat transfer.

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