<html><body><div style="font-family: times new roman, new york, times, serif; font-size: 14pt; color: #000000"><div>Dear Jeff Thornton</div><div>I would like to ask you if there is a type in TRNSYS wich simulate an MCP (material phase change) model</div><div>thank you</div><div><br></div><div><span name="x"></span>Kaouther Ben Nasr<br>Docteur Ingénieur\\Génie Énergétique<br>Maître assistant à l'ENAU <br>Chercheur au CRTEn\\Technopôle Borj Cédria<br>mobile: +216 53 48 44 38<span name="x"></span><br></div><div><br></div><hr id="zwchr"><div style="color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;" data-mce-style="color: #000; font-weight: normal; font-style: normal; text-decoration: none; font-family: Helvetica,Arial,sans-serif; font-size: 12pt;"><b>De: </b>"Jeff Thornton via TRNSYS-users" <trnsys-users@lists.onebuilding.org><br><b>À: </b>"Amirreza Heidary" <amirrezaheidarysbu@gmail.com>, "TRNSYS users mailing list at OneBuilding.org" <trnsys-users@lists.onebuilding.org><br><b>Envoyé: </b>Samedi 29 Avril 2017 16:52:42<br><b>Objet: </b>Re: [TRNSYS-users] problem with differential controller<br><div><br></div><div>Amirreza,</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">Real solar collectors do the same thing under certain circumstances. From a first glance I would say your dead bands are too tight - typically we see 10/2 not 5/2. It's also possible that your collector pump flow rate is too high. With collectors connected in series you typically have a pump flow rate the same as if you had only one collector. Collectors are designed for a given maximum flow rate for pressure drop reasons. For example, assume we had a collector that wanted 450 kg/h of flow and we had 6 in series. We would run the pump at 450 (each collector gets the 450 that way). You wouldn't run your pump at 2700 (450 x 6) or the pressure drop would be ridiculously high. If you have that high of a flow rate you'll get exactly what you are seeing in your project. With no flow the collector temperature is above the deadband but when the pump turns on the high flow rate causes the outlet temperature to drop below the lower deadband. The controller can't find a solution since both are correct and will oscillate between on and off.</div><div id="AppleMailSignature"><br></div><div id="AppleMailSignature">Jeff</div><div id="AppleMailSignature">TESS Inc<br><div><br></div>Sent from my iPhone</div><div><br>On Apr 29, 2017, at 2:36 AM, Amirreza Heidary via TRNSYS-users <<a href="mailto:trnsys-users@lists.onebuilding.org" target="_blank" data-mce-href="mailto:trnsys-users@lists.onebuilding.org">trnsys-users@lists.onebuilding.org</a>> wrote:<br><div><br></div></div><blockquote><div><div dir="ltr"><img width="0" height="0" class="mailtrack-img" style="float:right;" alt="" src="https://mailtrack.io/trace/mail/0a28719c14bd30ad7c353f53cc4b911f030d1d23.png?u=1249159" data-mce-style="float: right;" src="https://mailtrack.io/trace/mail/0a28719c14bd30ad7c353f53cc4b911f030d1d23.png?u=1249159">Dear All<div>I'm using a 5 collectors in series with a differential controller to turn on the pump when the difference of collector outlet and inlet temperatures is more than 5 and turn it off when it is less than 2.But the signal and collector output temperatures are fluctuating too much, also the signal is not compatible with temperature <a href="http://variations.as" target="_blank" data-mce-href="http://variations.as">variations.as</a> you can see in the following diagram, the signal is 1 when the outlet temperature is at maximum ! </div><div>(red line is collector outlet temperature and orange line is the controller signal)</div><div><img src="cid:ii_15bb8a2dac2c44f8" alt="Inline image 1" width="473" height="245" data-mce-src="cid:ii_15bb8a2dac2c44f8"></div><div><img src="cid:ii_15bb8a3362afa50c" alt="Inline image 2" width="473" height="222" data-mce-src="cid:ii_15bb8a3362afa50c"> <br clear="all"><div><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div><div style="text-align:right" data-mce-style="text-align: right;"><div style="text-align:left" data-mce-style="text-align: left;"><br></div><div style="text-align:left" data-mce-style="text-align: left;">--------------------------------------------------------------------------------------------------------------------------------------------------<br><img width="96" height="96" src="https://docs.google.com/uc?id=0B56a_joPrCZuYUg5aFkzTlR2dTg&export=download" src="https://docs.google.com/uc?id=0B56a_joPrCZuYUg5aFkzTlR2dTg&export=download"><br></div><div style="text-align:left;font-size:12.8px" data-mce-style="text-align: left; 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