[TRNSYS-users] pls give me your comments

[David BRADLEY via TRNSYS-users]

Ahmad,

   A few thoughts, not in any particular order:


-  The flow rate at which collectors are tested is not always the flow 
rate at which the manufacturer recommends that the collector be operated.

-  Some amount of pump chatter (rapid turning on and off) in the morning 
is normal.

- Type71 does not consider the thermal mass of the collector so it can 
be expected that the model reacts faster than perhaps a real life 
collector would. You can look at some of the solar collector models in 
the TESS Solar library for versions that do account for the thermal 
capacitance of the collector itself.

-  A 5C turn-on temperature difference is on the low side. If you want 
to reduce the chatter, you can increase the turn-on temperature 
difference and allow the collector outlet temperature to go higher 
before you turn on the pump.


kind regards,

  David



On 05/15/2017 00:58, ahmad abbasian via TRNSYS-users wrote:
>
> Hello
>
> I'm using an evacoaed tube solar collector (type 71). the colector 
> efficiency curve, area and test flow rate is based on a test report. 
> The collector pump is controlled by a differential controller to be 
> turned on when th difference of collector inelt and outlet 
> temperatures is higher than 5 and to be turned off when it is lower 
> than 2. Based on the area multiplied by test flow rate, the flow rate 
> of pump could be 375kgr/hour. But using this flow rate the pump is 
> turned off and turned on repeatedly, using low flow rate about 100 
> kgr/hour, the pump works well, but the outlet temperature is really low.
>
> attached picture named 100 is for using 100kgr/hour wter flow rate and 
> the other named 375 is for 100kgr/hour wter flow rate. As the 
> longitudinal IAM data was not in the report, the default IAM data of 
> trnsys is used.
>
> Please give me your comments to solve it
>
> Thank you
>
>
> ..............................................................................................
> Ahmad abbasianzadeh
> Solar energy Researcher
> *Harrisburg, Pensylvania*
>
>
>
>
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> TRNSYS-users at lists.onebuilding.org
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-- 
***************************
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
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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