makeFastHvacGreatAgain

[Dawac]

In addition to #309:
We would like to implement some features to the FastHVAC to hopefully make it a little bit more consistent and stable.

One of the goals is to

Tasks:

• mflow shall be defined as flow variable again
• new model for a generic splitter with variable split ratio between the ports
• implementation of a leakage massflow depending on a nominal flow for all components
• new demand model with conservation equation
• restructure the package order (see also Restructuring of the AixLib.FastHVAC.Components package #564)

[Dawac]

As far as we testet, one solution would be:
Within the enthalpy port:

• define the massflow as flow variable
• define the capacity, Temperature and enthalpy as stream variables (although temperature is redundant as it is coupled with the enthalpy)
• define a dummy pressure as potential variable

Within the massflowbalance:

• assign a fixed value to the pressure variable
• extend the balance equations with the nescassary instrem() expressions

[DaJansenGit]

The massflow is now implemented as a flow variable again.
This was possible by adding a dummy potential variable. It was removed before to solve problems with debugging (see #500) Changes made:

Rework enthalpy port:

• create dummy potential variable (hidden in results to prevent confusion)
• remove not needed temperature and specific heat capacity variables
• make enthalpy a stream variable and call it h_outflow

General changes:

• h_outflow at port a is always zero (no backflow in FastHVAC)
• h_outflow at port b described with inStream()
• rework splitter model

Todo: Models/packages to check and change:

• DHWHeatExchanger
• Radiators
• Fluid Source
• Pump
• HeatPump
• CHP
• Boiler
• Pipemodels
• Sensors
• Storages
• Sinks
• Valves

Todo in general:

• After merging into development and integration of Release v0.9 #740 move manifold to obsolete (not needed anymore due to flow variable does this by itself)
• create Conversion script for all the changes

[DaJansenGit]

We have a problem with the component AixLib.FastHVAC.HeatGenerators.BaseClasses.EvaporatorCondenserWithCapacity
For any reason the two missing equations for GOut and GInn throw an error when checking in the FastHVAC model but not in it's counterpart model AixLib.Fluid.HeatExchangers.EvaporatorCondenserWithCapacity.
If we set a default value for the variables GOut and GInn the model checks, but this seems quite dangerous to me.
Further investigation needed...