[TRNSYS-users] Types 2a and 2b

[Jeff Thornton]

Benjamin - try changing your time step.  15 minutes is pretty big for a collector system with a differential controller.  Are you using a collector with mass and pipes to slow down the response time?

Jeff Thornton
TESS

Sent from my iPhone

> On Aug 26, 2015, at 1:46 AM, Manrique Delgado Benjamin <benjamin.manriquedelgado at aalto.fi> wrote:
> 
> Hi David,
>  
> thanks for your answer. I followed your suggestion and unfortunately the problem is still there.  I set up the controller with 9/3, 10/2, and 11/1 which didn’t work. Going further would have significant impact on my results. Are there other ways to try to improve the operation of the controller?
>  
> Best regards,
> Benjamin
>  
>  
> From: David BRADLEY [mailto:d.bradley at tess-inc.com] 
> Sent: Tuesday, August 25, 2015 6:11 PM
> To: TRNSYS users mailing list at OneBuilding.org; Manrique Delgado Benjamin
> Subject: Re: [TRNSYS-users] Types 2a and 2b
>  
> Benjamin,
>   The Type2 Powell's Method mode is not appropriate for what you are trying to do. If you are getting more chatter in your collector control than you want or if you are running at times when the collector cannot sustain an outlet temperature higher than the tank temperature then you need to modify the temperature deadbands in the differential controller that turns on and off the collector pump. A "turn on" temperature difference of 10C and a "turn off" temperature difference of 2C would be good starting places.
> regards,
>  David
> 
> 
> On 08/25/2015 09:05, Manrique Delgado Benjamin wrote:
> Hi,
>  
> I am getting poor results by using Type2b to control a solar collector, since it operates at some time-steps when it shouldn’t (for example, when the temperature coming out from the tank is higher than the SC output temperature, effectively cooling the tank). I tried to switch to Type 2a, and changed to Powell’s method, but the model won’t run since I am using an Aquastat in a different part of the model, and that one requires the Successive substitution method.
> Has anyone faced this problem before?
> I am using a 0.25 hour resolution.
>  
> In advance, thanks for your help.
>  
> Best regards,
> Benjamin Manrique D.
>  
> 
> 
> 
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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
>  
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