.BuildingSystems.Fluid.Actuators.BaseClasses.equalPercentage

Information

This function computes the opening characteristics of an equal percentage valve.

The function is used by the model BuildingSystems.Fluid.Actuators.Valves.TwoWayEqualPercentage.

For y < delta/2, the valve characteristics is linear. For y > 3*delta/2 the valve characteristics is equal percentage. In between, a cubic spline is used to ensure that the valve characteristics is once continuously differentiable with respect to y.

Interface

function equalPercentage
  extends Modelica.Icons.Function;
  input Real y "Valve opening signal, y=1 is fully open";
  input Real R "Rangeability, R=50...100 typically";
  input Real l(min = 0, max = 1) "Valve leakage, l=Kv(y=0)/Kv(y=1)";
  input Real delta "Range of significant deviation from equal percentage law";
  output Real phi "Ratio actual to nominal mass flow rate, phi=Cv(y)/Cv(y=1)";
end equalPercentage;

Revisions

• April 11, 2016 by Michael Wetter:
  Corrected wrong hyperlink in documentation for issue 450.
• March 30, 2011 by Michael Wetter:
  Added zeroDerivative keyword.
• June 5, 2008 by Michael Wetter:
  First implementation.