[TRNSYS-users] Generating a control signal for a storage tank

[David BRADLEY]

Ali,
   I think what you are describing is just a simple thermostat in 
cooling mode (turn something on if a temperature rises above a certain 
setpoint and turn it off if the temperature falls below that setpoint). 
You can use Type2. If you are using Trnsys17 then there is already a 
Type2 proforma set up to do this in Controllers: Aquastat: Cooling Mode: 
Type2-AquastatC. If you have Trnsys16 you can set up Type2 to do the 
same. Input 2 becomes the setpoint (88C) and Input 1 will be connected 
from the temperature of the bottom node of your tank. The upper dead 
band will be 1C and the lower dead band will be -1C.

   If you have the TESS Controllers Library, you will find models of 
cooling aquastats in there as well.
Kind regards,
  David


On 2/24/2014 06:56, ali shirazi wrote:
>
> Dear Trnsys users,
>
>
> I am modeling a solar assisted absorption chiller. In this system, a 
> hot water storage tank is used to store solar thermal energy. The 
> cycle is also equipped with an auxiliary heater which is switched on 
> in case the tank temperature is lower than a certain value. I need to 
> generate a control signal (either 0 or 1) representing if the tank is 
> on or off. The following briefly describes the intended control strategy:
>
> The tank is on (control signal=1) if the bottom node temperature is 
> greater than 88 C and it is deactivated (control signal value=0) in 
> case the temperature at the top of the tank is less than 88 C. In this 
> case, the tank could be charged while the auxiliary heater is operating.
>
> I suppose an on/off differential controller would work for above 
> mentioned strategy (an equation box may be needed to be used as well) 
> but do not know how to make it work! I would really appreciate it if 
> you could give me hand in this regard.
>
> Looking forward to hearing from you soon.
>
>
> Regards,
>
>
> -- 
> *Ali shirazi*
> PhD Candidate
> School of Mechanical and Manufacturing Engineering
> The University of New South Wales
> Sydney NSW 2052
> Australia
> Email:
> ali.shirazee at gmail.com <mailto:ali.shirazee at gmail.com>
> a.shirazi at student.unsw.edu.au <mailto:a.shirazi at student.unsw.edu.au>
>
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at cae.wisc.edu
> https://mailman.cae.wisc.edu/listinfo/trnsys-users

-- 
***************************
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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