[TRNSYS-users] Type 952 - Convergence and flow/temperature drop

[Hélène THIEBLEMONT via TRNSYS-users]

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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