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RE: [EnergyPlus_Support] Exterior Radiative Heat Transfer Coefficients
Peter,
I think you have it right. These are linearized radiation coefficients that are comparable to convection coefficients.
For example the coefficient for sky is calculated using,
h_rad = Sigma * Emittance * View_Factor * ((TSurf**4)-(TSky**4))/(TSurf-TSky)
Brent
-----Original Message-----
From: Peter G. Loutzenhiser [mailto:post@xxxxxxxxxxx]
Sent: Thursday, December 02, 2004 10:03 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Exterior Radiative Heat Transfer Coefficients
Hello all,
I am looking some of the inputs for output variables in EnergyPlus and have
come across three outputs that I am not exactly certain what they mean. They
include 1) Surface Ext Rad to Air Coeff, 2) Surface Ext Rad to Sky Coeff, and
3) Surface Ext Ground Coeff. I have looked at the Engineering Manuel which
explains the calculation method thoroughly,but not the coefficients. Are these
coefficients used to calculate the impact of radiation in a form similar to the
exterior convective heat transfer coefficient? Is it reasonable to define the
radiative component of heat transfer as the sum of these values and make the
following calculation?:
qrad=h_rad*surface_area(T_outside_temp-T_exterior_surface_temp)
Or are the coefficients defined in a different way?
Thank you so much for your help.
Peter
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