setState_dTX does not work correctly

[modelica-trac-importer]

Reported by mdempsey on 4 Sep 2013 09:57 UTC
The function Modelica.Media.Interfaces.PartialLinearFluid.setState_dTX does not produce correct results (at least in Dymola) because the algorithm that is used to calculate state.p references state.T rather than the function input argument of T.

In the compiled model state.T is assigned after state.p is calculated which means the calculation of state.p sees the wrong temperature and therefore gives wrong results.

The current algorithm is:

state := ThermodynamicState(p=((d - reference_d) + 
  (state.T - reference_T)*beta_const*reference_d)
  /(reference_d*kappa_const) + reference_p, T=T);

This should be rewritten as:

state := ThermodynamicState(p=((d - reference_d) + 
  (T - reference_T)*beta_const*reference_d)
  /(reference_d*kappa_const) + reference_p, T=T);

---

Migrated-From: https://trac.modelica.org/Modelica/ticket/1267

[modelica-trac-importer]

Comment by beutlich on 29 Oct 2015 20:45 UTC
The proposed fix is applied by b06f0c9. Please cross-check and revert should the need arise.

I guess the regression results are affected by this commit. Actually I do not understand why such tickets (I mean rather critical and with a proposed patch for a single line change) are kept unconsidered and unaccepted for years.

[modelica-trac-importer]

Changelog modified by beutlich on 29 Oct 2015 20:45 UTC
Fixed the computation of the thermodynamic state in Modelica.Media.Interfaces.PartialLinearFluid.setState_dTX.state

[modelica-trac-importer]

Modified by beutlich on 29 Oct 2015 20:47 UTC

[modelica-trac-importer]

Changelog modified by beutlich on 29 Oct 2015 20:47 UTC
Fixed the computation of the thermodynamic state Modelica.Media.Interfaces.PartialLinearFluid.setState_dTX.state

[modelica-trac-importer]

Comment by hubertus on 29 Oct 2015 22:10 UTC
I have in the past regularly searched for tickets with me as an owner and the upcoming Milestone. I have never seen this ticket though. Not sure what went wrong: I usually fix such minor things as soon as I note them.