[TRNSYS-users] Type 2b Issue

Jeff Thornton thornton at tess-inc.com
Fri Oct 25 12:32:58 PDT 2013


 

<But when u exported the TRNSyS data to excel to check the result it
is noticed that sometimes pump is off even the above mentioned limit
(deltaTH=10 and delta TL= 2) is satisfied. I am attaching the excel file
and issue is highlighted in this file (sheet 1). Also TRNSYS file is
attached> 

You're not doing anything wrong. There are times when your
chosen deadbands aren't physically possible. Imagine a single solar
collector with a huge pump attached to it. When the pump is off, the
collector temperature is much higher than the tank during a sunny period
and the pump is turned on. However, with the pump on the collector
temperature is only 1 degree hotter than the tank due to the large flow
rate - so the pump turns off. Which solution is correct? They both are.
In situations like this, TRNSYS will iterate for a while and finally
"lock" the solution to one of the states. That's what you're seeing in
your results. 

Jeff 

---

Jeff Thornton 

_President - TESS LLC_ 

_22
N. Carroll Street, Madison WI USA 53703_ 

_Office: (608) 274-2577 Fax:
(608) 278-1475_ 

_www.tess-inc.com_ 

_E-Mail: thornton at tess-inc.com_


On 10/25/2013 4:33 am, Adeel Waqas wrote: 

> Dear Trnsys users 
> 
>
I facing problem while using controller Type 2b between solar water
heater and storage tank. i have spent several hours in understanding its
behavior but still i am confused. 
> 
> Issue is i have connected the
"UPPER INPUT TEMPERATURE" as collector outlet and "LOWER INPUT
TEMPERATURE" as outlet from storage tank heat exchanger. 
> 
> I have
set the DELTATH=10 and DELTA TL= 2 as i want that controller switch keep
the pump on between this two limits. 
> 
> But when u exported the
TRNSyS data to excel to check the result it is noticed that sometimes
pump is off even the above mentioned limit (deltaTH=10 and delta TL= 2)
is satisfied. I am attaching the excel file and issue is highlighted in
this file (sheet 1). Also TRNSYS file is attached 
> 
> I will be thanks
for the help and the suggestion and to know where I am wrong. 
> 
>
Regards
 
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