AixLib.Fluid.Movers.BaseClasses.Characteristics.efficiency

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

Flow vs. efficiency characteristics for fan or pump

## Information

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

η = s(V̇/rN, d),

where η is the efficiency, rN 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.

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