Re: [TRNSYS-users] negative radiation one 1 surface in type 56

To: Richard Thygesen <richard.thygesen@mdh.se>

Subject: Re: [TRNSYS-users] negative radiation one 1 surface in type 56

From: David BRADLEY <d.bradley@tess-inc.com>

Date: Wed, 13 Jun 2012 10:41:12 -0500

Cc: "TRNSYS-users@engr.wisc.edu" <TRNSYS-users@engr.wisc.edu>

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Richard,
The equation would probably work but I would try to hunt down the cause of the problem. When I have gotten this error, it is usually because I have messed something up about the orientation of the building; when I draw a building in Trnsys3D, I often draw it facing plan north (instead of true north) so I have to correct for that when I implement the building in the Studio. Look at the "turn" equation in the 3D_building example for how this can be accomplished.

A second possibility is a bad connection to Type56. Type56 takes total and beam radiation. If you give it a beam radiation and forget to connect the total radiation, Type56 will compute that there is a negative amount of diffuse radiation on the surface.

The other possibility is that there is actually a problem in the weather reading / processing component. To check this, remove the building from your project and put an online plotter on the radiation outputs of the weather reader. Check and make sure that they never go negative. If they do, please send me that project so that we can get it fixed.

Kind regards,
David

On 6/13/2012 06:56, Richard Thygesen wrote:

Hi again.

I guess it would be possible to solve this problem with an equation which never sends any negative values to type 56. What do you think about that?

Does that only cure the symptoms but not the problem?

Best regards

Richard Thygesen

Från: Richard Thygesen
Skickat: den 13 juni 2012 12:53
Till: TRNSYS-users@engr.wisc.edu
Ämne: [TRNSYS-users] negative radiation one 1 surface in type 56

Hi.

I have gotten an error message in my simulation stating that one surface in Type 56 have negative radiation.

This happened when I changed the sky model for diffuse radiation from Perez to Hay and Davies.

Has anyone encountered this problem before? How can I solve this?

I am using Trnsys version 17.

Best regards
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