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<p>Julien,</p>
<p> Convergence problems are often the result of not having enough
thermal capacitance in a loop. For instance if you have a massless
solar collector, a pump and a constant effectiveness heat
exchanger all in a loop and have neglected the pipes then there
are no components in the loop that have thermal capacitance and
the loop can change temperatures very very fast. You don't
necessarily need to go through the whole system and add in every
cm of piping but look at the warnings to find specifically what
components are not converging and then look at those loops to see
if you can add piping or a buffer tank to the loop to make it
numerically more stable.</p>
<p> You can also drop to a 1 minute time step as part of your
solution.</p>
<p> If you do go the route of using a time delay on inputs I would
suggest that you delay the values that your controllers are
watching. In my example above, for instance, you might delay the
outlet temperature of the collector that the controller is
watching. I would not advise delaying the temperature of the
collector that is being passed to the next component in the loop.<br>
</p>
<p>kind regards,</p>
<p> David</p>
<p> <br>
</p>
<div class="moz-cite-prefix">On 12/5/2022 7:23 AM, Julien Gambade
via TRNSYS-users wrote:<br>
</div>
<blockquote type="cite"
cite="mid:2076973647.48427086.1670246626339.JavaMail.zimbra@univ-ubs.fr">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div style="font-family: arial, helvetica, sans-serif; font-size:
12pt; color: #000000">
<div>Dear Trnsys users,<br>
</div>
<div><br data-mce-bogus="1">
</div>
<div>I have some problem with convergence issues. I am working
with a simulation with a duration of several months and a
timestep of 5 min. <br data-mce-bogus="1">
</div>
<div><br data-mce-bogus="1">
</div>
<div>For several time steps, some inputs do not converge and
after a certain time, the amount of warnings exceeds the
number of warnings before error.<br>
</div>
<div><br data-mce-bogus="1">
</div>
<div>Two options allowed me to end the simulation : increase the
number of warnings allowed and use Type "delayed inputs" (last
option results in a change in my outputs).<br
data-mce-bogus="1">
</div>
<div><br data-mce-bogus="1">
</div>
<div>Do you think the first solution is fine or should I go to
the second solution ? Or, does anyone know an other solution I
could try ?<br data-mce-bogus="1">
</div>
<div><br data-mce-bogus="1">
</div>
<div>Best regards,<br data-mce-bogus="1">
</div>
<div data-marker="__SIG_POST__">-- <br>
</div>
<div>
<div><strong>Julien GAMBADE</strong><br>
<strong>Doctorant</strong><br>
Institut de Recherche Dupuy de Lôme (UMR CNRS 6027)<br>
Centre de recherche Christian Huygens<br>
Rue de Saint-Maudé - 56100 Lorient - France<br>
<a class="moz-txt-link-abbreviated" href="mailto:julien.gambade@univ-ubs.fr">julien.gambade@univ-ubs.fr</a><br>
<a href="http://www.irdl.fr" target="_blank"
moz-do-not-send="true">www.irdl.fr</a><br>
</div>
</div>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
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</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
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<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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