An Enclosure Theory for Radiative Exchange Between Specularly and Diffusely Reflecting Surfaces

1962 ◽  
Vol 84 (4) ◽  
pp. 294-299 ◽  
Author(s):  
E. M. Sparrow ◽  
E. R. G. Eckert ◽  
V. K. Jonsson
Keyword(s):  
Heat Transfer ◽  
Convenient Method ◽  
Image Technique ◽  
New Formulation ◽  
Reflecting Surfaces ◽  
Specular Surfaces ◽  
Radiative Exchange

A systematic and convenient method has been devised for the calculation of the radiant interchange within an enclosure containing both specularly reflecting and diffusely reflecting surfaces. The new formulation makes use of simple properties of the images formed by plane mirrors, and this does away with the need to keep account of individual rays as they are reflected on the specular surfaces. With this image technique, heat-transfer calculations for a specular-diffuse enclosure are no more difficult than those for a fully diffuse enclosure. The method is illustrated by application to specific enclosure geometries.

A Stochastic Approach for Radiative Exchange in Enclosures With Nonparticipating Medium

1984 ◽  
Vol 106 (4) ◽  
pp. 690-698 ◽  
Author(s):  
M. H. N. Naraghi ◽  
B. T. F. Chung
Keyword(s):  
Heat Transfer ◽  
Approximate Solutions ◽  
Stochastic Approach ◽  
Absorption Factor ◽  
Heat Transfer Characteristics ◽  
Markov Chain Theory ◽  
Different Types ◽  
Chain Theory ◽  
Specular Surfaces ◽  
Radiative Exchange

A stochastic method is developed for calculating radiation interchange in enclosures with a finite number of isothermal surfaces but without a participating medium. Different types of surface properties are considered. They are diffuse and specular surfaces. In this work, a stochastic n model is proposed that is based on the Markov chain theory and leads to some explicit matrix relationships for the absorption factor from which the heat transfer characteristics of the enclosure can be determined. The present approach provides an exact solution as long as the necessary view factors can be determined. The accuracy of approximate solutions can be improved as n increases.

Geometric Optimization of Radiant Enclosures Containing Specular Surfaces

2003 ◽  
Vol 125 (5) ◽  
pp. 845-851 ◽  
Author(s):  
K. J. Daun ◽  
D. P. Morton ◽  
J. R. Howell
Keyword(s):  
Design Methodology ◽  
Optimization Design ◽  
Numerical Algorithms ◽  
Geometric Optimization ◽  
Trial And Error ◽  
Design Problems ◽  
Design Iteration ◽  
Optimization Methodology ◽  
Reflecting Surfaces ◽  
Specular Surfaces

This paper presents an optimization methodology for designing radiant enclosures containing specularly-reflecting surfaces. The optimization process works by making intelligent perturbations to the enclosure geometry at each design iteration using specialized numerical algorithms. This procedure requires far less time than the forward “trial-and-error” design methodology, and the final solution is near optimal. The radiant enclosure is analyzed using a Monte Carlo technique based on exchange factors, and the design is optimized using the Kiefer-Wolfowitz method. The optimization design methodology is demonstrated by solving two industrially-relevant design problems involving two-dimensional enclosures that contain specular surfaces.

Simulation of Radiation Heat Transfer of Three Dimensional Participating Media by Radiative Exchange Method

2008 ◽  
Author(s):  
Mohammad Hadi Bordbar ◽  
Timo Hyppa¨nen
Keyword(s):  
Heat Transfer ◽  
Balance Equation ◽  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Radiation Balance ◽  
Scattering Media ◽  
Radiation Heat ◽  
Exchange Method ◽  
Participating Media ◽  
Radiative Exchange

This paper describes the theoretical bases of the Radiative Exchange Method, a new numerical method for simulating radiation heat transfer. By considering radiative interaction between all points of the geometry and solving the radiation balance equation in a mesh structure coarser than the structure used in computational fluid flow calculation, this method is able to simulate radiative heat transfer in arbitrary 3D space with absorbing, emitting and scattering media surrounded by emitting, absorbing and reflecting surfaces. A new concept is introduced, that of the exchange factors between the different elements that are necessary for completing the radiative balance equation set. Using this method leads to a set of algebraic equations for the radiative outgoing power from each coarse cell being produced and the result of this set of equations was then used to calculate the volumetric radiative source term in the fine cell structure. The formulation of the exchange factor for a three-dimensional state and also a mesh size analysis that was conducted to optimize the accuracy and runtime are presented. The results of this model to simulate typical 3D furnace shape geometry, is verified by comparison with those of other numerical methods.

Thermal insulation effect of green façades based on calculation of heat transfer and long wave infrared radiative exchange

Measurement ◽  
2021 ◽  
pp. 110555
Author(s):  
Ratih Widiastuti ◽  
Juliana Zaini ◽  
Wahyu Caesarendra ◽  
Georgios Kokogiannakis ◽  
Siti Nurul Nadia Binti Suhailian
Keyword(s):  
Heat Transfer ◽  
Thermal Insulation ◽  
Long Wave ◽  
Insulation Effect ◽  
Long Wave Infrared ◽  
Radiative Exchange

A Three-Dimensional Variable Geometry Countercurrent Model for Whole Limb Heat Transfer

1992 ◽  
Vol 114 (3) ◽  
pp. 366-376 ◽  
Author(s):  
M. Zhu ◽  
S. Weinbaum ◽  
D. E. Lemons
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Approximate Theory ◽  
Cross Sectional ◽  
Warm Environment ◽  
Axial Temperature ◽  
Cutaneous Tissue ◽  
New Formulation ◽  
Dimensional Variable

A new formulation of the combined macro and microvascular model for heat transfer in a human arm developed in Song et al. [1] is proposed using a recently developed approximate theory for the heat exchange between countercurrent vessels embedded in a tissue cylinder with surface convection [2]. The latter theory is generalized herein to treat an arm with an arbitrary variation in cross-sectional area and continuous bleed off from the axial vessels to the muscle and cutaneous tissue. The local microvascular temperature field is described by a “hybrid” model which applies the Weinbaum-Jiji [3] and Pennes [4] equations in the peripheral and deeper tissue layers, respectively. To obtain reliable end conditions at the wrist and other model input parameters, a plethysmograph-calorimeter has been used to measure the blood flow distribution between the arm and hand circulations, and hand heat loss. The predictions of the model show good agreement with measurements for the axial surface temperature distribution in the arm and confirm the minimum in the axial temperature variation first observed by Pennes [4] for an arm in a warm environment.

Transient Coupled Heat Transfer in Three-Layer Composite with Opaque Specular Surfaces

2002 ◽  
Vol 16 (3) ◽  
pp. 297-305 ◽  
Author(s):  
Jian-Feng Luo ◽  
Xin-Lin Xia ◽  
He-Ping Tan ◽  
Timothy W. Tong
Keyword(s):  
Heat Transfer ◽  
Coupled Heat Transfer ◽  
Layer Composite ◽  
Specular Surfaces

The Efficiency at Maximum Power Output of a Carnot Engine with Heat Leak

1995 ◽  
Vol 23 (2) ◽  
pp. 157-165 ◽  
Author(s):  
F. Moukalled ◽  
R. Y. Nuwayhid
Keyword(s):  
Heat Transfer ◽  
Power Output ◽  
Maximum Power ◽  
Heat Leak ◽  
Suggested Model ◽  
Maximum Power Output ◽  
Transfer Processes ◽  
Newton’S Law ◽  
New Formulation ◽  
Special Case

Endoreversible thermodynamics are used for studying the performance of Carnot engines with heat leak. This is done by adding a heat leak term into a variation of the model suggested by DeVos [1]. Heat transfer across the engine is assumed to occur via a conduction/convection mechanism and Newton's law of cooling is employed to model the heat transfer processes. The efficiency at maximum power output is found to be deeply affected by the rate of heat leak. Moreover, the Curzon-Ahlborn relation [2] is shown to represent a special case of the new formulation. Since the suggested model allows more flexibility in predicting actual engines' performance, its use is recommended in thermodynamics courses.

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