[TRNSYS-users] type for simulating MCP materials

[via TRNSYS-users]

Dear Jeff Thornton 
I would like to ask you if there is a type in TRNSYS wich simulate an MCP (material phase change) model 
thank you 

Kaouther Ben Nasr 
Docteur Ingénieur\\Génie Énergétique 
Maître assistant à l'ENAU 
Chercheur au CRTEn\\Technopôle Borj Cédria 
mobile: +216 53 48 44 38 

----- Mail original -----

De: "Jeff Thornton via TRNSYS-users" <trnsys-users at lists.onebuilding.org> 
À: "Amirreza Heidary" <amirrezaheidarysbu at gmail.com>, "TRNSYS users mailing list at OneBuilding.org" <trnsys-users at lists.onebuilding.org> 
Envoyé: Samedi 29 Avril 2017 16:52:42 
Objet: Re: [TRNSYS-users] problem with differential controller 

Amirreza, 

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. 

Jeff 
TESS Inc 

Sent from my iPhone 

On Apr 29, 2017, at 2:36 AM, Amirreza Heidary via TRNSYS-users < trnsys-users at lists.onebuilding.org > wrote: 




Dear All 
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 variations.as you can see in the following diagram, the signal is 1 when the outlet temperature is at maximum ! 
(red line is collector outlet temperature and orange line is the controller signal) 


-------------------------------------------------------------------------------------------------------------------------------------------------- 

amirrezaheidary 
master student of energy systems Engineering 
Sharif university of technology 
Tehran-Iran 
E-mail address : 

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heidari at energy.sharif.edu 


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a mirrezaheidarysbu at gmail.com 
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