[TRNSYS-users] GEOSURF values of walls and windows

[David BRADLEY]

Pu,

  I can imagine some configurations of nine airnodes that might not 
result in getting same value of SQCOOL as QCOOL when those nine airnodes 
are combined into one especially as concerns radiation exchange between 
the surfaces. I would suggest you send your *.tpf and *.b18 to your 
distributor so that they can check to see if there is not some 
assumption difference that is causing the results that you are seeing.

  It might be worth reading a bit in the Type56/TRNBuild documentation 
about GEOSURF. That variable specifies the fraction of beam radiation 
entering a zone that falls on each surface of the zone. I am not very 
familiar with the details of how the default value of GEOSURF is 
determined. It is of course a function of the building geometry and not 
something that should be modified in order to bring the results of one 
model closer to those of another.

kind regards,

  David


On 07/01/2022 21:54, Huijie Pu via TRNSYS-users wrote:
> Hello！
>
> I divided a large space into nine areas, i.e. in TRNBuild, one zone 
> with nine airnodes, but the output NTYPES33-SQCOOL value of the model 
> is always higher than the output NTYPES31-QCOOL value of the full 
> large space model, but according to the actual , the two values should 
> be the same. Both models have the same settings, neither have any 
> gains set, and the weather files are the same. I don't understand what 
> is causing this?
> I found that the difference between these two values is related to the 
> GEOSURF values of walls and windows, and is most related to the value 
> of GEOSURF for wall with boundary conditions that the wall is the 
> floor.  The sum of the GEOSURF  values of each airnode is 1. So that 
> the cooling demand value of the two models is the same, which is need 
> to modify the geosurf value of each air node?
>
> kind regards,
> Pu
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy System Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com
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