[TRNSYS-users] Internal and external shading factors in Type 56

[Fieberg, Christian]

Dear Knut,

 

I´m not quite sure about the internal shading in TRNSYS, but in my understanding your description is quite reasonable. Outside shading reflects the radiation and thus keeps the radiation heat flux outside of your building. Internal shading allows the radiation heat flux to enter the building and is "trapped" between window and internal shading, which is heated. From the shading heat is transferred by convection into the zone.

 

Hope this helps.

 

Best regards,

 

Christian

 

Von: knut.erik.enerstvedt at niva.no [mailto:knut.erik.enerstvedt at niva.no] 
Gesendet: Dienstag, 10. November 2009 10:11
An: trnsys-users at engr.wisc.edu
Betreff: [TRNSYS-users] Internal and external shading factors in Type 56

 

Hello all,

 

I'm using Type 56 to develop a model of a greenhouse which has controllable inside screens to reduce incoming and outgoing radiation. I have used the "internal shading factor" of the windows with an input variable to achieve this, since the screens are actually on the inside of the greenhouse. However, the internal shading device does not have quite the effect I expected. It does not seem to reduce solar radiation hitting the zone, so that temperatures rise very high on warm and sunny days. It does however seem to reduce temperature loss at night, but this could be due to the additional thermal resistance. By testing the "external shading factor" instead, I found that this device has the effect I want, blocking out radiation and keeping temperatures down on hot days. Can someone please tell me if I have misunderstood the concept of internal shading? Does it not prevent outside solar radiation from hitting the zone after passing through the windows?

 

Best regards,

Knut Erik Enerstvedt



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