AixLib.Fluid.HeatExchangers.BaseClasses.PartialEffectiveness

# .AixLib.Fluid.HeatExchangers.BaseClasses.PartialEffectiveness

Partial model to implement heat exchangers based on effectiveness model

## Information

Partial model to implement heat exchanger models.

Classes that extend this model need to implement heat and mass balance equations in a form like

      // transferred heat
      Q1_flow = eps * QMax_flow;
      // no heat loss to ambient
      0 = Q1_flow + Q2_flow;
      // no mass exchange
      mXi1_flow = zeros(Medium1.nXi);
      mXi2_flow = zeros(Medium2.nXi);

Thus, if medium 1 is heated in this device, then `Q1_flow > 0` and `QMax_flow > 0`.

## Revisions

- April 27, 2023, by Michael Wetter:
  Set nominal and min attributes for capacity flow rates.
  Moved assignments from `initial equation` to parameter declaration. This avoids a warning in Dymola 2023x about non-literal nominal values.
  This is for #3360.
- February 21, 2019, by Filip Jorissen:
  Revised implementation of all equations such that a binding equation is used. I.e. we set the variable value at the variable definition instead of using the equation section. This allows overwriting the equation when extending the model.
  See #1102.
- April 30, 2018, by Filip Jorissen:
  Set `prescribedHeatFlowRate1=true` and `prescribedHeatFlowRate2=true`.
  See #907.
- June 9, 2015 by Michael Wetter:
  Changed type of `T_in1` and `T_in2` to `Medium1.Temperature` and `Medium2.Temperature` to avoid an error because of conflicting start values if Buildings.Examples.ChillerPlant.BaseClasses.Controls.Examples.ChillerSetPointControl is translated using pedantic mode in Dymola 2016. This is for #426.
- October 8, 2011, by Michael Wetter:
  Set `show_T=false` to avoid state events near zero flow.
- August 31, 2011, by Michael Wetter:
  Removed unused variables `gai1` and `gai2`.
- February 12, 2010, by Michael Wetter:
  Changed model structure to implement effectiveness-NTU model.
- January 28, 2010, by Michael Wetter:
  Added regularization near zero flow.
- October 2, 2009, by Michael Wetter:
  Changed computation of inlet temperatures to use `state_*_inflow` which is already known in base class.
- April 28, 2008, by Michael Wetter:
  First implementation.

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