[TRNSYS-users] "Advanced" tempering valve

[Damien Casetta]

Hi all,

I am modeling a hot water system with a tempering valve (step 1 : a
fraction of the cold flow is sent to the heat source to be heated up, step
2 : the other is mixed with the resulting hot flow). However, in my case, I
can't use the built-in component "tempering valve". Indeed, another hot
flow is added between step 1 and 2 so the component equations are not valid
anymore. Yet, I haven't found any satisfactory method to handle this. Here
is what I have tried out :

- The flow diverter parameter Y (step 1) is set by user-provided equations
(equations box), function of temperatures and flow rates in the loop + set
temperature

--> convergence problems

- The flow diverter parameter Y (step 1) is set by a controller (PID or
iterative). However, when the set temperature is reached, tracking error
tends to 0 and so does the control signal (connected directly to the valve
opening Y). It is not the solution at a given time step. Controller output
should not be linked direcly to the valve opening (but to its derivative I
guess).

--> stability problems (it oscillated around the set temperature)


Do you have any idea how to solve this simple problem?


Please let me know if I am not clear enough.



Thanks in advance,



Regards,


*Damien CASETTA*
*INSA Lyon / Génie Energétique et Environnement*
*ENERTECH / Cabinet SIDLER*
*26160 Félines sur Rimandoule*
*Tél & Fax : 04 75 90 18 54*
*Courriel : **damien.casetta at gmail.com* <damien.casetta at gmail.com>
*Site : **www.enertech.fr* <http://www.enertech.fr/>
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