Re: [EnergyPlus_Support] View Factors

["Michael J. Witte" <mjwitte@xxxxxxxx>]

Are there any internal gains (people, lights, etc.) that have a radiant 
component?  How are you reporting or inferring the amount of radiant exchange. 
While it is true that the total radiant exchange should sum to zero, the 
magnitude should change.  Lower absorptances become a resistance to radiant 
heat exachange.  So, I would expect to see more heat flowing from warm to cool 
surfaces when the absorptance is high, and less flow when the absorptance is 
low.  Is that consistent with the results you are getting?

Mike


On 21 Oct 2004, at 6:46, Peter G. Loutzenhiser wrote:

> 
> I am modeling a small interior room with no windows--so no additional 
> irradiation enters the space, and I have specified no thermal mass in the 
> space.  I look at the calculation method for radiation exchange and appears to
> be an energy balance between all the surface.  I would expect from an energy
> balance that the heat transfer from some wall would be negative and some to be
> positive and, therefore, from a first law balance assuming steady-state
> conditions, the total heat exchange due to radiation would sum to zero. 
> However, I have found that radiation exchange varies significantly (for this
> size of space) when I alter the thermal absorbtance.  Perhaps I am misinformed
> and am completely missing an assumption or not factoring in additional elements
> used in the algorithm, but how can this be?
> 
> Thanks in advance,
> Regards,
> Peter Loutzenhiser
> ISU 
> 
> 
> 
> 
> 
> 
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> 
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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