.BuildSysPro.BaseClasses.HeatTransfer.Components.LinearExtLWR

Information

Hypothesis and equations

The solar flux with long wavelength radiation has two sources : the environment and the sky. Different hypothesis have been made :

• The flux from the sky is supposed isotropic.
• The exchanges between the wall, the sky and the environment are supposed to depend only on the skyViewFactor and the long wavelength emissivity.
• The sky and the environment are supposed to be isothermal black bodies.

The radiative net fux exchanged between a wall and the outside is linearized with the function below :

Where :

and are respectively the Stefan-Boltzmann constant and the emissivity of the wall. Furthermore , and are representatives constants of the sky, environment and outside surface temperatures. Using the values :

• K,
• = 263.15 K , from the BRUNT correlation,
• and K,

it gives :

Finally, we get :

Bibliography

TF1 CLIM2000

Instructions for use

Typical values for epsilon (from BodyRadiation model) :

   aluminium, polished    0.04
   copper, polished       0.04
   gold, polished         0.02
   paper                  0.09
   rubber                 0.95
   silver, polished       0.02
   wood                   0.85..0.9

Known limits / Use precautions

Verify that the conditions of use are close enough to K and = 263.15 K.

Validations

Modèle validé - Gilles PLESSIS 12/2012

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Licensed by EDF under a 3-clause BSD-license
Copyright © EDF 2009 - 2023
BuildSysPro version 3.6.0
Author : Gilles PLESSIS, EDF (2012)
Initial model : BodyRadiation, Anton Haumer, Copyright © Modelica Association, Michael Tiller and DLR.
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