.AixLib.Fluid.Movers.BaseClasses.Characteristics.efficiency

Information

This function computes the fan or pump efficiency for given normalized volume flow rate and performance data. The efficiency is

η = s(V̇/r_N, d),

where η is the efficiency, r_N is the normalized fan speed, V̇ is the volume flow rate, and d are performance data for fan or pump efficiency.

Implementation

The function s(·, ·) is a cubic hermite spline. If the data d define a monotone decreasing sequence, then s(·, d) is a monotone decreasing function.

Interface

function efficiency
  extends Modelica.Icons.Function;
  input AixLib.Fluid.Movers.BaseClasses.Characteristics.efficiencyParameters per "Efficiency performance data";
  input Modelica.Units.SI.VolumeFlowRate V_flow "Volumetric flow rate";
  input Real d[:] "Derivatives at support points for spline interpolation";
  input Real r_N(unit = "1") "Relative speed";
  input Real delta "Small value for switching implementation around zero speed";
  output Real eta(unit = "1", final quantity = "Efficiency") "Efficiency";
end efficiency;

Revisions

• December 2, 2016, by Michael Wetter:
  Removed min attribute as otherwise numerical noise can cause the assertion on the limit to fail.
  This is for #606.
• November 22, 2014, by Michael Wetter:
  Corrected documentation as curve uses V̇ as an independent variable.
• September 30, 2014, by Filip Jorissen:
  Changed polynomial to be evaluated at V_flow instead of r_V.
• April 19, 2014, by Filip Jorissen:
  Changed polynomial to be evaluated at r_V/r_N instead of r_V to properly account for the scaling law. See #202 for a discussion and validation.
• September 28, 2011, by Michael Wetter:
  First implementation.