.Buildings.Fluid.HeatExchangers.BaseClasses.epsilon_C

Information

This function computes the heat exchanger effectiveness, the Number of Transfer Units, and the capacity flow ratio for given capacity flow rates.

The implementation allows for zero flow rate. As CMin_flow crosses delta*CMin_flow_nominal from above, the Number of Transfer Units and the heat exchanger effectiveness go to zero.

The different options for the flow regime are declared in Buildings.Fluid.Types.HeatExchangerFlowRegime.

Interface

function epsilon_C
  input Modelica.Units.SI.ThermalConductance UA "UA value";
  input Modelica.Units.SI.ThermalConductance C1_flow "Enthalpy flow rate medium 1";
  input Modelica.Units.SI.ThermalConductance C2_flow "Enthalpy flow rate medium 2";
  input Integer flowRegime "Heat exchanger flow regime, see  Buildings.Fluid.Types.HeatExchangerFlowRegime";
  input Modelica.Units.SI.ThermalConductance CMin_flow_nominal "Minimum enthalpy flow rate at nominal condition";
  input Modelica.Units.SI.ThermalConductance CMax_flow_nominal "Maximum enthalpy flow rate at nominal condition";
  input Real delta = 1E-3 "Small value used for smoothing";
  output Real eps(min = 0, max = 1) "Heat exchanger effectiveness";
end epsilon_C;

Revisions

• January 10, 2018, by Michael Wetter:
  Removed outputs Z and NTU as they are not used by other models. Removed if statement that can cause a discontinuous derivative.
• July 7, 2014, by Michael Wetter:
  Changed the type of the input flowRegime from Buildings.Fluid.Types.HeatExchangerFlowRegime to Integer. This was done to have the same argument list as Buildings.Fluid.HeatExchangers.BaseClasses.epsilon_ntuZ, in which the type had to be changed.
• July 6, 2014, by Michael Wetter:
  Removed unused import statement.
• February 20, 2010, by Michael Wetter:
  First implementation.