Issue1287 DHW model

[lucasverleyen]

Fixes #1287

Issues as described in #1287 have been addressed. The unit test for the old example has been removed and two new unit tests have been added for the two new examples covering the two DHW tap models. The reference results can be found in #1287 .

[jelgerjansen]

@lucasverleyen thanks for refactoring this model. I've focused on the implementation of PartialTap for now. Please have a look at my remarks and use that feedback in the other models as well if possible. When that's done, I'll do a second review.

[lucasverleyen]

@louisher thanks a lot for the review. I have implemented and resolved all of your suggestions, except 1. @jelgerjansen can you give your opinion?

[jelgerjansen]

@lucasverleyen I did some quick checks with a new implementation for the mass flow calculation. The old implementation gives small but unrealistic results around the transition are (m>m_set, blue curve below).
I removed the delTSca component and its inputs and replaced the mFloHot component (and its inputs) by the following RealExpression:
Modelica.Blocks.Sources.RealExpression mFloHot(y=smooth(2, if noEvent(THot<TSet) then m_flow_set else m_flow_set*(TSet - TCol)/(THot.T - TCol)))
This results in a twice differentiable function (red). I therefore propose to keep the latter implementation, as this gives better results and is more understandable for other users.

The simulation results below have the a constant m_flow_set of 0.1kg/s and TSet of 45°C.

[lucasverleyen]

@jelgerjansen I fully agree with your suggestion! It is indeed more elegant and easier to interpret.

[lucasverleyen]

@jelgerjansen all comments have been addressed. Unit tests pass. If you agree with the implementation of the discomfort calculation in the Tap.mo example, this pull request is ready to be merged.