<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p>Amirreza,</p>
<p> I would try three things. <br>
</p>
<p> One is to set the mass flow rate and inlet temperature to the
active layer as INPUTS to Type56 (they may already be set that
way) and then run some cases where you use a forcing function or
an equation to switch between a high inlet temperature and a low
inlet temperature and between flow on and flow off. If the flow
rate and inlet temperature are constant then sometimes it can be
hard to see what their effect is because everything is steady
state. In doing this, make sure that your weather conditions are
cold; if the building's ambient condition is close to 26C then
putting 26C water into the active layer is not going to have much
of a visible effect<br>
</p>
<p> The second thing I would recommend is to put a layer of
insulation on the side of the concrete that you are NOT trying to
condition with the active layer. We ran into this same situation
where there was a mezzanine that had a radiant floor. It was
impossible to control the temperature of the mezzanine area
without insulating the underside of that floor (which was also the
exposed ceiling below). It may be that a lot of your energy is
going up instead of down. <br>
</p>
<p> Lastly, instead of watching the air temperature, look at the
surface temperature of the concrete. It should be quite close to
the temperature of the active layer. That surface temperature
should be more directly impacted by the active layer than the air
temperature is</p>
<p>best,</p>
<p> David</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 1/6/2023 3:56 PM, Amirreza Heidari
via TRNSYS-users wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAMtrc5R2UWeB7LeO6UgK4E5ajb7um9-DmDrY2KKv+mC1_Ty4xQ@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">
<div class="gmail_default" style="color:rgb(11,83,148)"><font
style="" size="4" face="times new roman, serif">Hello,</font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif"><br>
</font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif">I am trying to model
a ceiling heating system in type 56b. The actual heating
system is actually some hot water heating panels that are
located in the ceiling. The actual sizes or thickness of
layers are not important, and I only expect the model to
reflect a realistic behavior. To model the ceiling heating
system, I putted an active layer between two layers of
common concrete. The specifications of active layer, common
concrete, and the ceiling structure are shown below.
However, the model does not show a reasonable behavior
because: </font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif"><br>
</font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif">1- The
temperature increment of the zone is very small (with 11000
L/H flowrate and 26 C inlet water for a 50 m2 zone)</font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif">2- The temperature
increment of zone does not change with the change of inlet
flowrate</font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif">3- When I change the
specifications of active layer (for example by reducing the
pipe spacing), the minimum required flowrate of water
reaches to unreasonable high values </font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><br>
</div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif">I tried to get a
reasonable behavior by trying following actions: </font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif">1- <b>Reducing the
thermal capacity of common cement:</b> It did not work
because when I have a big surface with very low thermal
capacity, the solar radiation from windows increases the
zone temperature to very high values (e.g. 30 C). The same
happens with the use of low-capacitance layers like hollow
brick.</font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif">2- <b>Trying the
chilled ceiling: </b>Although it is not exactly what I
need, I tried it to see if it can have a reasonable
behavior. But it does not do any change of indoor air
temperature (maybe it is only coded for cooling!) </font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif">3- <b>Huge increase
in inlet flowrate: </b>Does not change anything !!!</font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif"><br>
</font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif">I have attached the
.b18 file as well. The inlet temperature and flow to the
active layers are as inputs (from other components). The
simulation timestep is 30 minuts. Would you please let me
know why the zone temperature variation versus the inlet
water temperature is extremely low and how I can fix it? </font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><font
size="4" face="times new roman, serif"><br>
</font></div>
<div class="gmail_default" style="color:rgb(11,83,148)"><img
src="cid:part1.7A30iL0c.FTkl2MLx@tess-inc.com"
alt="image.png" class="" width="517" height="445"><br>
</div>
<div class="gmail_default" style="color:rgb(11,83,148)"><br>
</div>
<div class="gmail_default" style="color:rgb(11,83,148)"><img
src="cid:part2.fKPPS7g5.u2TIKq67@tess-inc.com"
alt="image.png" class="" width="517" height="432"><br>
</div>
<div class="gmail_default" style="color:rgb(11,83,148)"><br>
</div>
<div class="gmail_default" style="color:rgb(11,83,148)"><img
src="cid:part3.RqxSLpJA.Q9vlV0eF@tess-inc.com"
alt="image.png" class="" width="517" height="422"><br>
</div>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
TRNSYS-users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:TRNSYS-users@lists.onebuilding.org">TRNSYS-users@lists.onebuilding.org</a>
<a class="moz-txt-link-freetext" href="http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org">http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org</a>
</pre>
</blockquote>
<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy System 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>
</body>
</html>