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<p>Pu,</p>
<p> The definition of a zone (or more precisely in Trnsys an
"airnode") is a volume of a building that can be characterized as
having a single temperature because the air is well mixed. While
we are able to physically place airnodes next to each other,
TRNSYS is not designed to automatically determine the convection
between them. There are some tools (TRNFlow, CONTAM, and COMIS)
that can determine the airflow between adjacent airnodes. All
three tools are called "bulk air flow models" and all make the
assumption that the resistance to air flow between airnodes is
high in comparison to the resistance to airflow within the
airnode's volume and that flow is driven by pressure and
temperature differences. <br>
</p>
<p> If you have a single large volume that you want to break up
into smaller volumes in order to model temperature distribution
within the larger volume then there are basically two options. One
is that you can use a bulk air flow model to try and get some idea
of the air movement even though the situation is one in which
there is as little resistance to air flow between nodes as there
is within nodes. This is particularly difficult because bulk air
flow models only allow for unidirectional airflow through large
horizontal openings, a situation that often results in numerical
instabilities in the model not to mention modeled behavior that is
pretty clearly unreasonable. <br>
</p>
<p> The other option that I have seen used is to model the full
space using a CFD tool under a wide variety of boundary conditions
so that you can essentially map the internodal air flows that
result from the boundary conditions that will develop over the
course of the simulation. I have seen some couplings between
Trnsys and CFD tools but typically the CFD engine takes a very
long time to compute the flow rates and it is not practical to
allow Trnsys to call it every time step.</p>
<p>kind regards,</p>
<p> David</p>
<p> <br>
</p>
<div class="moz-cite-prefix">On 11/14/2021 03:42, Huijie Pu via
TRNSYS-users wrote:<br>
</div>
<blockquote type="cite"
cite="mid:219f2b43.d2c.17d1dd347ea.Coremail.huijiepu@163.com">
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<p style="margin: 0px;">Hello,</p>
<div style="margin: 0px;"> I am using TRNSYS to simulate a
zonal model, that is, a large space is divided into five
subzones. You know, in practice, there is no physical
partition between adjacent areas. In the manual of TRNSYS, I
don't see the relevant description of the zonal model, but in
the relevant literature on implementing the zonal model with
TRNSYS, it is pointed out that there is a virtual wall between
the two adjacent thermal zones of TRNSYS, that is, the air in
the two adjacent zones is not circulating, and the air flow in
the adjacent zones needs to be realized with air flow software
such as contam or comis, So as to truly reflect the large
circulation of air flow in the actual large space. I don't
know if this is correct, so I want to ask you.</div>
<div style="margin: 0px;">
<div style="margin: 0px;"><span style="font-family: Helvetica,
"Microsoft Yahei", verdana;"><br>
</span></div>
<div style="margin: 0px;"><span style="font-family: Helvetica,
"Microsoft Yahei", verdana;">kind regards,</span></div>
<div style="margin: 0px;"><span style="font-family: Helvetica,
"Microsoft Yahei", verdana;">Pu</span></div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
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<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI 53703 USA
P:+1.608.274.2577
<a class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.tess-inc.com">http://www.tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.trnsys.com">http://www.trnsys.com</a></pre>
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