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Hélène,
I would go back to the version that has all Type31s then
replace one of those Type31s with a 952. Put an online plotter
that shows the temperature and flow rate of liquid into and out of
the Type952. Go carefully through the parameters and make sure
that they are all reasonable values and that there isn't something
like a very low deep earth temperatures. Hopefully the results
will make sense at which point you should replace a second Type31.
Type65 can be a very powerful debugging tool to make sure that the
system is operating as expected.
Have a look also at the time step and the flow rate through the
pipes. If you have a long time step and a short pipe then it may
be that the convergence problems are because liquid flows through
the pipe network multiple times per timestep and causes numerical
instability in the results.
kind regards,
David
On 09/12/2017 04:56, Hélène THIEBLEMONT
via TRNSYS-users wrote:
Good morning everybody,
I am modeling a district
heating and cooling system. Therefore, in order to model the
pipes, I am using the Type 952 from TESS.
However, after a
comparison with the use of a simple pipe (Type 31), I have
two problems:
- First, I have a significant
period of my simulation that does not convergence. To give
you an example, if I change only 5 pipes from Type 31 to
952 my simulation does not converge 34% of the time and if
I change all of them my simulation does not converge 100%
of the time, even in reducing the time step to 0.1hr. Is
there anything to do that may help TRNSYS to converge in
that situation?
- Secondly, and what is
particularly strange to me: when I replace my types 31 by
952, the results become completely crazy. I’ve attached
two files with the temperatures and flow that go in and
out, with the type 31 and the type 952. As you can see,
the results are logical with the type 31, and the flow and
the temperature drop close to 0 with the type 952 without
any reason. Do you have any idea of what may cause this
kind of problems?
Thank you very much for
your time and help,
Sincerely
Hélène
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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@tess-inc.com
http://www.tess-inc.com
http://www.trnsys.com
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