[TRNSYS-users] PID controlled valve

[David BRADLEY via TRNSYS-users]

Miguel,

  If your 3-way valve is acting as a tempering valve then there are some 
tempering valve components in the TESS controllers library that you can 
use. The difficulty in using a PID controller in a situation like yours 
is that the simulation time step is quite long in comparison to the time 
constant of the valve. If you really want to model PID then it is far 
easier to do with something where the time constant of the process being 
modeled is long in comparison to the time step of the simulation. The 
tempering valve model knows the temperature of the sources (A and B) and 
knows the temperature that you are trying to mix to so it can compute 
analytically the steady state solution; the ratio of A and B that will 
result in C.

kind regards,

  David



On 03/21/2017 08:30, Miguel Angel Reyes via TRNSYS-users wrote:
>
> Hi all,
>
> Is there any existing type of a controlled valve by using a PID.
>
> In my problem I would like using three-ways valve where ports A and B 
> are joining into an outlet C port. I would like controlling the outlet 
> temperature of port C by modifying the opening of port B (this is from 
> a hot recirculating stream).
>
> Kind Regards
>
> ---------------------------------------------------
>
> Miguel
>
>
>
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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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