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<p>Hooman,</p>
<p> I doubt that Type2 is doing the wrong thing. It might be worth
reading the reference manual section on Type2 if my reply does not
make sense but my guess is that early in the morning there is
enough solar energy to heat up the stagnant collector fluid above
the Type2 turn on temperature difference. However, as soon as the
pump starts flowing the outlet temperature drops again because
there is not enough solar to maintain the outlet temperature of
flowing liquid above the temperature difference. The controller
probably oscillates back and forth between the possible decisions
(pump on vs pump off) and cannot converge so it "sticks." In your
case it sticks in the pump-off position so you see a bit
temperature spike until there is enough solar radiation to
maintain the outlet temperature above the turn-on temperature
difference.</p>
<p> If you are using Type1 then it is important to be aware that
this collector model ignores the thermal capacitance of the
collector materials themselves as well as that of the fluid
contained in the collector. As a result the collector reacts to
changes very fast (sometimes unrealistically fast). You could use
Type539 from the TESS Solar library if you have access to it. That
collector model accounts for the capacitance of the collector
itself. Also make sure that you are using a reasonably short
timestep (1-5 minutes) and that there is not some unrealistic
mismatch between the size of the tank, the area of the collector
array and the flow rate of the pump.</p>
<p>kind regards,</p>
<p> David</p>
<p><br>
</p>
<br>
<div class="moz-cite-prefix">On 09/15/2018 04:48, Hooman Azad via
TRNSYS-users wrote:<br>
</div>
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<p class="MsoNormal"><span
style="font-size:14.0pt;color:#2E75B6;mso-style-textfill-fill-color:#2E75B6;mso-style-textfill-fill-alpha:100.0%">Dear
friends<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;color:#2E75B6;mso-style-textfill-fill-color:#2E75B6;mso-style-textfill-fill-alpha:100.0%">Please
check my simple circuit. A 150 kg tank is supposed to be
maintained at 60 degrees all year. A flat plate collector
has been employed. When you run the simulation (file FPC1),
you see some sharp rises of collector outlet temperature, as
high as 400 degrees, which are obviously wrong. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;color:#2E75B6;mso-style-textfill-fill-color:#2E75B6;mso-style-textfill-fill-alpha:100.0%">If
you remove the type2b controller and, for example, control
the pump with type14h (file FPC2), the sharp rises
disappear. It seems type2b is responsible for the errors in
the first case. Thank you very much for your kind help.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;color:#2E75B6;mso-style-textfill-fill-color:#2E75B6;mso-style-textfill-fill-alpha:100.0%">Hooman<o:p></o:p></span></p>
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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
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>
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