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William,<br>
I would be very careful in using the Type60 with an internal heat
exchanger and low flow rates, particularly if you are anywhere close
to laminar flow. I have run into some problems with its internal
calculation of the heat exchanger UA as well. If possible, I would
recommend that you use Type534 from the TESS Storage Libary. In my
experience, the UA calculation for that tank model's internal heat
exchanger is more robust.<br>
Best,<br>
David<br>
<br>
<br>
On 11/10/2011 04:32, <a class="moz-txt-link-abbreviated" href="mailto:William.Logie@solarenergy.ch">William.Logie@solarenergy.ch</a> wrote:
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<p class="MsoNormal">Dear TRNSYS folk,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I was wondering if anyone can shed some
light on Type60, in particular low flow operation of the
immersed heat exchanger model (IHX). I’m using the 16.01.0003
edition of TRNSYS and 2005-01-31 – Mku version of Type60.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve been happily simulating high-flows
(>40kg/hr per m^2 collector area) but run into
non-convergence warnings (and infinite loops) with, for
example, a specific collector flow of 10kg/hr; storage volume
400 litres with 25 nodes and a simulation time step between 3
and 6 mins; <a moz-do-not-send="true"
href="http://sel.me.wisc.edu/trnsys/mailinglist/archive2004/msg00640.html">http://sel.me.wisc.edu/trnsys/mailinglist/archive2004/msg00640.html</a>.
I have tried reducing the flow rate to a minute and even less
but non-convergence persists (for an annual simulation that
doesn’t abort I get between 2 and 5 thousand warnings). Some
exemplary energy balances (measured with Type60) are as
follows;<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">10kg/hr:<o:p></o:p></p>
<p class="MsoNormal">Q_coll + Q_aux = 13934081.86 kJ<o:p></o:p></p>
<p class="MsoNormal">Q_losses + Q_dhw = 13920759.15 kJ<o:p></o:p></p>
<p class="MsoNormal">Q_coll + Q_aux – Q_losses – Q_dhw = Q_err =
13322.71 kJ<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">50kg/hr:<o:p></o:p></p>
<p class="MsoNormal">Q_coll + Q_aux = 13961476.57 kJ<o:p></o:p></p>
<p class="MsoNormal">Q_losses + Q_dhw = 13947209.16 kJ<o:p></o:p></p>
<p class="MsoNormal">Q_coll + Q_aux – Q_losses – Q_dhw = Q_err =
14267.41 kJ<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is this all within reason? If not, any
tips?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Kind regards,<o:p></o:p></p>
<div class="MsoNormal" style="text-align:center" align="center"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="DE-CH">
<hr align="center" size="2" width="100%"></span></div>
<p class="MsoNormal"><b><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="DE-CH">William Logie</span></b><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""
lang="DE-CH"><br>
Forschung / Research</span><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="DE-CH"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""
lang="DE-CH">Institut für Solartechnik SPF: <a
moz-do-not-send="true"
href="http://www.solarenergy.ch/spf.php?lang=de&fam=44&tab=3"
title="http://www.solarenergy.ch/spf.php?lang=de&fam=44&tab=3"><span
style="color:blue">Adresse</span></a> / <a
moz-do-not-send="true"
href="http://www.solarenergy.ch/spf.php?lang=de&fam=41&tab=1"
title="http://www.solarenergy.ch/spf.php?lang=de&fam=41&tab=1"><span
style="color:blue">Website</span></a><br>
Hochschule für Technik Rapperswil HSR<br>
Tel. +41 55 222 48 34<br>
Fax +41 55 222 48 44</span><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="DE-CH"> <o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA
P:+1.608.274.2577
F:+1.608.278.1475
<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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