[TRNSYS-users] Glass shading overhang with dynamic reflection coating

[David BRADLEY]

Tom,
   The "incident receiver radiation" term includes both beam radiation 
and diffuse radiation. Shading devices often either occlude the beam 
radiation completely or not at all whereas the diffuse radiation is 
reduced (more or less) by the view factor between the receiver and the 
sky. In the case of a venetian blind, the beam radiation is reduced by 
the blind but may or may not be reduced by the same fraction as the 
diffuse radiation. In fact I think that is rather the point of a 
venetian blind: it blocks the beam radiation more than it blocks the 
diffuse but still allows some to come through depending on the angle of 
the blades.
Regards,
  David


On 4/19/2013 03:13, Tom B wrote:
> Dear all,
>
> When I took a look at the multizone building with an overhang as it is 
> made by the wizard in the Simulation Studio, I noticed that it uses 
> both the "Incident receiver radiation" and the "Beam radiation on 
> receiver" as an input for the multizone building. I was wondering 
> whether anyone can explain to me why it needs both the Incident 
> receiver radiation, which already is all the radiation on the window 
> if I'm not mistaking, and in addition needs the beam radiation.
>
> I'm asking because I want to replace the Type 34 overhang component 
> with an Excel lookup table with transmission values of a venetian 
> blind, and I was assuming that multiplying these total light 
> transmission values of the shade with the total incident radiation on 
> the shade would give me the total transmitted energy, and there would 
> be no need to know the beam radiation transmission individually as 
> well. Can anyone tell whether or not this assumption is correct and if 
> not, why the beam radiation is needed in addition to the total radiation?
>
> Thank you in advance for your time and effort.
>
> Kind regards,
>
> Tom Bouwhuis
>
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

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

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