[TRNSYS-users] Multizone building

[David BRADLEY]

The method by which airflow between adjacent air nodes is computed is by 
adding a TRNFlow or CONTAM (Type97) model in parallel with your Type56 
building model. You'll define airflow paths in between your air nodes. 
Both of those engines, however, are based on the assumption that the 
resistance to airflow between two air nodes (i.e. through the paths that 
you define) is high in comparison to the resistance to airflow of the 
nodes themselves. Think of two large rooms connected by a small opening; 
the opening offers much more resistance to airflow than do the rooms 
themselves. Now thing of a long narrow room that is broken into two 
adjacent air nodes. The airflow resistance offered by the connection is 
basically the same as the air flow resistance of the nodes themselves. 
Both TRNFlow and CONTAM do a better job predicting airflow in the first 
case than they do in the second.

There are certainly reasons why you might want to break up a large zone 
into a number of adjacent airnodes, natural ventilation being one of the 
most common. Given that the simulation methods for estimating the mixing 
airflow are somewhat limited, I would only split that zone into multiple 
airnodes if there was a very compelling reason to do so.

kind regards,

  David


On 08/29/2021 22:34, Huijie Pu via TRNSYS-users wrote:
>
> Hello!
>
>
> I built a large space area model, which is 8 meters long, 8 meters 
> wide and 3 meters high. The space area is provided with four air 
> nodes. There are no adjacent walls between the air nodes, and only two 
> outer walls are provided in each area. Is it correct to set the area 
> with multiple air nodes in this way? Do you need to set adjacent walls 
> between each air node? How to determine the coupled flow between these 
> air nodes?
>
>
> Thank you very much.
>
>
>
>
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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

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

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