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Santeri,<br>
Pumps in TRNSYS set the downstream flow rate according to their
rated flow rate and the value of their current control signal. Apart
from checking for mass balance problems, they ignore their inlet
mass flow rate. When there are loops that have multiple pumped
branches, you have to be particularly careful to make the flow
splitting decisions based on the flow rate that is currently
entering the flow diverter. I would recommend that you remove the
connections from the diverter to the pumps. Then connect the outlet
flow rate of every device in the loop to an online plotter and make
sure that you understand the outlet flow at each component. Make
sure that the mass balance is preserved. Next, reconnect the flow
diverter to the pumps and see whether the mass balance is still
preserved. If it is not, there may not be enough thermal capacitance
in your loop. Controllers may be making decisions based on
unconverged temperatures. <br>
Best,<br>
David<br>
<br>
<br>
<div class="moz-cite-prefix">On 9/19/2012 05:54, Santeri Siren
wrote:<br>
</div>
<blockquote
cite="mid:CAF-s-b+dsDOWFuuubi4FG4ML4NpxLtSAhAhQAuBGXirGAoCvcQ@mail.gmail.com"
type="cite">Dear all,<br>
<br>
I have a problem with the mass balances of my system. In my proct
a flow diverter divides the waterflow into two separate pipes.
.After the flowdiverter both pipes go to their own pumps. The flow
diverter is controlled according to the ratio of mass flows
produced by the pumps. After the pumps comes heating loads. After
that the waterflows are connected in a flow mixer and the water is
being heated in a heatpump. <br>
<br>
The problem is that Trnsys gives mass balance warnings for both
pumps. When I check the mass flows of the pumps, they some times
are even larger than the rated flow of the pump.I think the
problem has something to do with the flow diverter...<br>
<br>
Can someone give me advice how to fix this problem and make the
mass flows balanced. I have attached a demonstrative picture of my
project.<br>
<br>
best regards. <br>
Santeri Siren<br>
<br>
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<br>
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<pre class="moz-signature" cols="72">--
***************************
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
<a class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.tess-inc.com">http://www.tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.trnsys.com">http://www.trnsys.com</a></pre>
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