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Damien,<br>
The tempering valve controller model is quite a simple equation
involving the ratio of temperatures. It is derived from an energy
balance (the sum of all the m_dot*Cp*T terms). I would think that if
you know the flow rate and temperature of the water that is being
added between steps 1 and 2, you could resolve the energy balance
and determine a new control algorithm for the tempering valve.<br>
Best,<br>
David<br>
<br>
<br>
<div class="moz-cite-prefix">On 5/14/2013 01:42, Damien Casetta
wrote:<br>
</div>
<blockquote
cite="mid:CA+b-pK5YKOQ20c8EDcS7MCyq=NuSYeRDzNFP2yDs+CWBfjP_BA@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>Hi all, </div>
<div><br>
</div>
<div>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 : </div>
<div><br>
</div>
<div style="">- 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</div>
<div style=""><br>
</div>
<div style="">
--> convergence problems </div>
<div style=""><br>
</div>
<div style="">- 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). </div>
<div style=""><br>
</div>
<div style="">--> stability problems (it oscillated around
the set temperature)</div>
<div style=""><br>
</div>
<div style=""><br>
</div>
<div style="">Do you have any idea how to solve this simple
problem? </div>
<div style="">
<br>
</div>
<div style=""><br>
</div>
<div style="">Please let me know if I am not clear enough. </div>
<div style=""><br>
</div>
<div style=""><br>
</div>
<div style=""><br>
</div>
<div style="">Thanks in advance,</div>
<div style=""><br>
</div>
<div style="">
<br>
</div>
<div style=""><br>
</div>
<div style="">Regards,</div>
<div><br>
</div>
<br clear="all">
<div>
<div dir="ltr">
<div style="font-family:'Times New Roman'" align="left"><font
face="Arial"><strong><em>Damien CASETTA</em></strong></font></div>
<div style="font-family:'Times New Roman'" align="left">
<font face="Arial"><strong><em>INSA Lyon / Génie
Energétique et Environnement</em></strong></font></div>
<div style="font-family:'Times New Roman'" align="left"><font
face="Arial"><strong><em>ENERTECH / Cabinet SIDLER</em></strong></font></div>
<div style="font-family:'Times New Roman'" align="left"><font
face="Arial"><strong><em>26160 Félines sur Rimandoule</em></strong></font></div>
<div style="font-family:'Times New Roman'" align="left"><font
face="Arial"><strong><em>Tél & Fax : 04 75 90 18 54</em></strong></font></div>
<div style="font-family:'Times New Roman'" align="left"><font
face="Arial"><strong><em>Courriel : </em></strong></font><a
moz-do-not-send="true"
href="mailto:damien.casetta@gmail.com" target="_blank"><font
face="Arial"><strong><em>damien.casetta@gmail.com</em></strong></font></a></div>
<div style="font-family:'Times New Roman'" align="left"><font
face="Arial"><strong><em>Site : </em></strong></font><a
moz-do-not-send="true" href="http://www.enertech.fr/"
target="_blank"><font face="Arial"><strong><em>www.enertech.fr</em></strong></font></a></div>
</div>
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</div>
<br>
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<br>
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<br>
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