[TRNSYS-users] Cross flow ventilation

[David BRADLEY]

Loïc,

  Sorry for misinterpreting your question. I think you do need to delete 
the adjacent surfaces and get one large radiation zone that includes 
your stack of airnodes. Then you use the "coupling between airnodes" 
popup to define the rate at which air moves from one of the air nodes to 
the other.

  If you drew your building in SketchUp you can draw in the adjacent 
surfaces between the airnodes and assign them as the "virtual surface" 
category option (sorry I can't check the exact language of the option; 
my SketchUp install is giving me problems right now and I can't launch 
it to check). In any case if those "adjacent" surfaces are set as 
virtual then they won't be brought into the TRNBuild model and thus you 
won't have to delete them manually but will still have the integrity of 
the airnodes.

kind regards,

  David


On 1/13/2023 11:27 AM, Loic Tachon wrote:
> Thanks for the answer, in my case I know the ventilation cross flow 
> induced by the stack effect and I suppose that this flow cross all the 
> zone.
>
> Do I need to delete the horizontal air nodes adjacent surface (surface 
> inside the radiation zone) to get just one radiation zone ?
>
> If we know the flow between airnodes, is it better to put it via 
> coupling between zones pop up ?
> image.png
>  or through surface definition, adjacent coupling air flow (if the 
> adjacent surfaces are not deleted) ?
>
> image.png
>
> Thanks a lot.
>
> Regards,
>
> Le ven. 13 janv. 2023 à 16:56, David BRADLEY <d.bradley at tess-inc.com> 
> a écrit :
>
>     Loïc,
>
>       The best way to address airflow within a building is to couple
>     your Type56 simulation either with TRNFlow or CONTAM (Type97). The
>     basic idea is that you build a parallel model to your Type56
>     containing information about the airflow openings between the
>     airnodes (a radiation zone can contain multiple airnodes,
>     especially where there is an atrium like you have described).
>     TRNFlow or CONTAM then take the air node temperatures as well as
>     the wind speed and geometry of the building and determine the
>     amount of air flow that results between the air nodes. Large
>     horizontal openings are challenging because both TRNFlow and
>     CONTAM treat air flow through a horizontal opening as
>     unidirectional. Still, it is by far the most rigorous way of
>     treating the situation.
>
>     kind regards,
>
>      David
>
>
>     On 1/13/2023 8:29 AM, Loic Tachon via TRNSYS-users wrote:
>>     Dear Trnsys community,
>>
>>     I want to simulate the stack effect in a high room with high
>>     thermal gain.
>>
>>     For this, I have 1 zone and 5 thermal air nodes in the z
>>     direction to get the temperature at several heights.
>>     image.png
>>     How can I do this and avoid that TRNSYS see ceiling between the
>>     zone ? Do I need to delete the horizontal surface for zone 2-3-4
>>     ? Or do I put mass less horizontal surface ?
>>
>>     As Well, how do I do the cross flow ventilation ? Do I use the
>>     couple mass flow between zones ?
>>     image.png
>>
>>      or I put a coupling air flow (same that natural ventilation mass
>>     flow) for the horizontal surface ?
>>     image.png
>>
>>     Thanks a lot.
>>
>>     Best regards,
>>
>>     -- 
>>     *Dr. Loïc Tachon *
>>     (+33) 6 7440-0536 (France)
>>
>>     *
>>     *
>>
>>     _______________________________________________
>>     TRNSYS-users mailing list
>>     TRNSYS-users at lists.onebuilding.org
>>     http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org
>
>     -- 
>     ***************************
>     David BRADLEY
>     Principal
>     Thermal Energy System Specialists, LLC
>     3 North Pinckney Street - suite 202
>     Madison, WI  53703 USA
>
>     P:+1.608.274.2577
>     d.bradley at tess-inc.com
>
>     http://www.tess-inc.com
>     http://www.trnsys.com
>
>
>
> -- 
> *Dr. Loïc Tachon *
> (+33) 6 7440-0536 (France)
>
> *
> *

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

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

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