.BuildingSystems.Fluid.HeatExchangers.BaseClasses.PartialEffectiveness

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.