Re: [TRNSYS-users] differential controller's problem

[Jeff Thornton <thornton@tess-inc.com>]

Vajihe,

I’m curious as to why you have equations between the collector and tank.  You should add some capacitance to your loop via pipes as well and have a timestep in the order of a minute or two.  Send me your project and I’ll take a look.

Jeff

Sent from my iPhone

On Sep 4, 2019, at 12:58 AM, Vajihe Davoodi <v.davoodi91@gmail.com> wrote:

Hi Jeff,

 Thanks for your recommendation.

I have prepared a schematic from my simulation which is attached.

It's a part of my solar absorption chiller model.

Thermal storage inlet water temperature (colder fluid) is 103 C but its outlet temperature is variable. I should define a differential controller which prepare temperature more than which enter to the solar collectors (outlet cod water of thermal storage).

I have changed thermal storage properties to these:

volume of thermal storage= 1800 litr

boiling point= 150 C

and controller with 10 and 2 , upper and lower dead band respectively.

now I want to know why sometimes solar energy is negative in my simulation, it means that the outlet temperature of collectors is less than inlet temperature. By this anybody can help me to solve my problem? 

<image.png>

  

On Wed, Sep 4, 2019 at 12:43 AM Jeff Thornton via TRNSYS-users <trnsys-users@lists.onebuilding.org> wrote:

Vajije,

It's a little difficult to understand from your e-mail what you are trying to do with the differential controller.  Can you provide a schematic of your system and maybe a diagram of the controls you wish to implement?  That will help the users here better answer your question.

 

Jeff

 

---
Jeff Thornton
President - TESS LLC
3 N. Pinckney Street, Suite 202, Madison WI USA 53703
Office: (608) 274-2577  Fax: (608) 278-1475
www.tess-inc.com
E-Mail: thornton@tess-inc.com

On 09/03/2019 1:48 pm, Vajihe Davoodi via TRNSYS-users wrote:

Hi all,

I have simulated a solar absorption chiller, I should run it for different thermal storage inlet temperatures for example with inlet temperature of 103 C. then I want the outlet temperature of thermal storage doesn't above the inlet temperature. I have defined a differential controller but it doesn't effect on outlet temperature, I changed upper and lower dead band temperature different times but the outlet temperature didn't change.

if someone can help me please tell me why it doesn't work?   

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