Calculation of the Shape Factor From a Small Rectangular Plane to a Triangular Surface Perpendicular to the Rectangular Plane Without a Common Edge

1993 ◽  
Vol 115 (2) ◽  
pp. 117-119 ◽  
Author(s):  
H. L. Noboa ◽  
D. O’Neal ◽  
W. D. Turner
Keyword(s):  
Heat Transfer ◽  
Analytical Model ◽  
Radiative Heat Transfer ◽  
Shape Factor ◽  
Radiative Heat ◽  
Mirror Image ◽  
Graphical Form ◽  
Factor Algebra ◽  
Common Edge ◽  
Small Rectangle

In developing an analytical model of radiative heat transfer inside attics, the necessity of calculating the shape factor from a small rectangle to a triangular plane may arise. This paper describes a methodology of calculation for such a shape factor from simple relations using shape-factor algebra. The shape factor is calculated using a mirror image of the triangular surface, in such a way that the small rectangular plane is positioned symmetrical between the two triangular surfaces. Numerical results are presented in graphical form.

Control of Net Radiative Heat Transfer With a Variable-Emissivity Accordion Tessellation

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Rydge B. Mulford ◽  
Vivek H. Dwivedi ◽  
Matthew R. Jones ◽  
Brian D. Iverson
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Analytical Model ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Radiative Properties ◽  
Apparent Temperature ◽  
The Impact ◽  
Specular Surfaces ◽  
Cavity Effect

Origami tessellations have been proposed as a mechanism for control of radiative heat transfer through the use of the cavity effect. This work explores the impact of a changing projected surface area and varying apparent radiative properties on the net radiative heat transfer of an accordion fold comprised of V-grooves. The net radiative heat transfer of an accordion tessellation is obtained by a thermal energy balance at the cavity openings with radiative properties of the cavities given as a function of various cavity parameters. Results of the analytical model are experimentally confirmed. An accordion tessellation, constructed of stainless-steel shim stock, is positioned to achieve a specified fold angle and placed in a vacuum environment while heated by Joule heating. A thermal camera records the apparent temperature of the cavity openings for various fold angles. Results are compared to apparent temperatures predicted with the analytical model. Analytically and experimentally obtained temperatures agree within 5% and all measurements fall within experimental uncertainty. For diffusely irradiated surfaces, the decrease in projected surface area dominates, causing a continuous decrease in net radiative heat transfer for a collapsing accordion fold. Highly reflective specular surfaces exposed to diffuse irradiation experience large turn-down ratios (7.5× reduction in heat transfer) in the small angle ranges. Specular surfaces exposed to collimated irradiation achieve a turn down ratio of 3.35 between V-groove angles of 120 deg and 150 deg. The approach outlined here may be extended to modeling the net radiative heat transfer for other origami tessellations.

scholarly journals A simplified analytical model of radiative heat transfer in open cell foams

2014 ◽  
Vol 547 ◽  
pp. 012045
Author(s):  
A Andreozzi ◽  
N Bianco ◽  
S Cunsolo ◽  
V Naso ◽  
M Oliviero
Keyword(s):  
Heat Transfer ◽  
Analytical Model ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Open Cell ◽  
Open Cell Foams

Intensification of Radiative Heat Transfer and Development of New Types of Tube Furnaces

2005 ◽  
Vol 36 (6) ◽  
pp. 475-480 ◽  
Author(s):  
A. V. Stepanov ◽  
N. I. Sulzhik ◽  
V. N. Nikolaenko
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Tube Furnaces
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