[TRNSYS-users] VirtualSurface

Thu May 6 01:28:10 PDT 2021

Dear Marion,

Thank you for your expert feedback, I have corrected my sketch (enclosed),
could you write me if now it is ok?

Kind regards,
Karol

From: Marion Hiller [mailto:Hiller at Transsolar.com] 
Sent: Monday, May 3, 2021 9:13 AM
To: TRNSYS users mailing list at OneBuilding.org
<trnsys-users at lists.onebuilding.org>
Cc: David BRADLEY <d.bradley at tess-inc.com>; Karol BANDURSKI
<karol.bandurski at put.poznan.pl>
Subject: AW: [TRNSYS-users] VirtualSurface

Karol,

General information on virtual surfaces:

-          The reason for adding a virtual surface is that the volume of an
airnode has to be closed with respect to geometry such that the volume of
the airnode can be calculated. 

-          A virtual surface is not part of the thermal model  of Type 56  
-> no heat transfer, no interaction with shortwave and longwave radiation

-          Solar radiation is distribution to all surfaces of all airnodes
of thermal zone 
(Note: virtual surfaces aren't considered as they are not part of the
thermal model)

-          longwave radiation is distributed to and exchanged with
a) all surfaces of an airnode if the longwave radiation mode = standard   
b) all surfaces of all airnodes of thermal zone if the longwave radiation
mode = detailed
(Note: virtual surfaces aren't considered as they are not part of the
thermal model)

Thus, your sketch lacks the distinction regarding the longwave radiation
mode.
The sketch on the right for one zone with two airnodes is correct for
longwave radiation mode = detailed only.

Best,

Marion

Dipl.-Ing. Marion Hiller

+49 711 679 76 32 |  <mailto:hiller at transsolar.com> hiller at transsolar.com

Transsolar 

Stuttgart | Munich | Paris | New York

Transsolar Energietechnik GmbH | Curiestrasse 2 | 70563 Stuttgart | Germany

CEO: Matthias Schuler, Thomas Auer, Stefan Holst, Dieter Schnelle 

Registered at Amtsgericht Stuttgart HRB 23347 | USt-IdNr.: DE 152272639

Von: TRNSYS-users <trnsys-users-bounces at lists.onebuilding.org
<mailto:trnsys-users-bounces at lists.onebuilding.org> > Im Auftrag von David
BRADLEY via TRNSYS-users
Gesendet: Freitag, 30. April 2021 18:23
An: TRNSYS users mailing list at OneBuilding.org
<trnsys-users at lists.onebuilding.org
<mailto:trnsys-users at lists.onebuilding.org> >
Cc: David BRADLEY <d.bradley at tess-inc.com <mailto:d.bradley at tess-inc.com> >;
Karol BANDURSKI <karol.bandurski at put.poznan.pl
<mailto:karol.bandurski at put.poznan.pl> >
Betreff: Re: [TRNSYS-users] VirtualSurface

Karol,

 I think your picture is correct. 

 The process for setting it up can be a little confusing. My understanding
of how to set up the second case is to draw both Zone1 and Zone2 separated
by a VirtualSurface in Trnsys3d. I assume there is some way of doing the
same in TRNLizard but I'm afraid I'm not familiar with that tool. Once you
import the *.idf file into TRNBuild, the virtual surface will disappear. You
then add Zone2 to Zone1 so that they become two airnodes of a single zone.
To do this, you open the zone/airnode that you're going to move and you
click on the button in the upper left corner that looks like a u-shaped
arrow.

 Since the virtual surface that separates the two airnode has disappeared
you no longer have an adjacent surface through which to define the air flow
coupling. Instead, you click on the "coupling" button in the airnode window
(upper right) and define the coupling there.

best,

 David

On 04/30/2021 08:01, Karol BANDURSKI via TRNSYS-users wrote:

Dear Expert,

I have tackled this topic a few times but I am still not sure if I
understand the idea of Virtual Surface.

Could you write me if enclosed sketch properly describe heat exchange in the
zone in the context of Virtual surface?

Kind regards,

Karol

--------------------------------------------------------------------

Karol BANDURSKI Ph.D.

Faculty of Environmental and Energy Engineering

Division of Heating, Air Conditioning and Air Protection

Poznan University of Technology

 <http://www.put.poznan.pl/~karol.bandurski> www.put.poznan.pl/~karol.
bandurski

 <https://www.researchgate.net/profile/Karol_Bandurski>
https://www.researchgate.net/profile/Karol_Bandurski

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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

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

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