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Re: [TRNSYS-users] Detailed radiation model

Dear Christoph,

Thank you very much for your reply. Finally, I have checked the surfaces and I can perform the simulations without any error.

However, I would also like to ask how I could obtain the mean radiant temperature of the 3 airnodes in the model I described in the previous email. In the manual (chapter 5.2.4.12 Radiation Modes) it is written that the longwave radiation distribution is available only for thermal zones, not airnodes - this might justify the reason why I got the same values for different airnodes.

Thus, do you know if there is the way to overcome this problem?

I would be grateful for any hints.

Kind regards,
Lukasz

2018-07-02 10:40 GMT+02:00 hotline via TRNSYS-users <trnsys-users@lists.onebuilding.org>:

Dear Lukasz,

 

As the error says, is your building geometry not closed or not convex (Manual 5-Multizone, 5.2.7.12. Zone Radiation Modes). This problem can’t be caused by your virtual surfaces.

Please make sure that your building is convex and closed!

 

Best,

Christoph

 

Von: TRNSYS-users [mailto:trnsys-users-bounces@lists.onebuilding.org] Im Auftrag von Lukasz Watly via TRNSYS-users
Gesendet: Freitag, 29. Juni 2018 09:42
An: TRNSYS users mailing list at OneBuilding.org <trnsys-users@lists.onebuilding.org>
Cc: Łukasz Wątły <lukaszwatly92@gmail.com>
Betreff: [TRNSYS-users] Detailed radiation model

 

Dear All,

 

I have desgined in SketchUP a single thermal zone with 3 airnodes placed on different heights (10, 60, 110 cm). I used a Virtual Surface option to model the surfaces which, after exporting them to TRNBuild, could dissapear.

 

In my simulation of the zone, I would like to obtain three values of Tairnode, Toperative and mean radiant temperature for each airnode. Unfortunately, when I perform simulation in TRNSYS, all three values of mean radiant temperatures are the same. This I did with the radiation model set to standard.

 

When I am trying to use the detailed radiation model, I got two error informations:

 

- ==== zone GROUND_FLOOR_10... ... ERROR in summing view factors of surface 4. Please check geometry!!!.

 

- Error while creating VFM file.
+++ Note: Zones have to be convex and closed volumes.
          Surfaces must have an outwarding normal.

 

This causes the situation that I am unable to open the .vfm file in TRNSYS and cannot get the mean radiant temperature values.

 

I assume that the problem is caused by the fact that my model might not be a closed volume, due to the virtual surfaces I have created in SketchUP. So my question is, is there another way to get the MRT values for each airnodes separetely?

 

The view factor of surface 4 is set to 0.5 automatically, as it is one of the vertical walls.

 

Thank you in advance for your help.

 

Kind regards,

Lukasz Watly

 


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