Re-introduce pressure drop calculation based on medium properties

[marcusfuchs]

As discussed in this weeks conference call, we may want to go back from the current pressure drop pre-calculation to the one we had before and instead add a new medium model to the Annex 60 library that better represents water used in district heating. I opened an issue at iea-annex60/modelica-annex60#511 for the new medium model.

In this issue here I suggest to revert the changes introduced by #30. As #30 contains quite a lot of commits, I would opt for quickly pushing a manual code change rather than a real git revert.

[bramvdh91]

What is the current status of this issue? I think this was solved in #49, but do we have any progress on the dp calculation?

Crazy idea: we could include the heat gains by the friction dissipation in the pipes if we have the design value ;)

[bramvdh91]

Some ToDo's from Carles' comment under #71

• [ ] propagate the HydraulicDiameter parameters (ReC, roughness, fac, allowFlowReversal, ...)
• [ ] dp_nominal is not used anymore. We can remove it or suggest to change HydraulicDiameter.