.Buildings.Fluid.Movers.BaseClasses.Characteristics.pressure

Information

This function computes the fan static pressure raise as a function of volume flow rate and revolution in the form

Δp = r_N²   s(V̇/r_N, d),

where Δp is the pressure rise, r_N is the normalized fan speed, V̇ is the volume flow rate and d are performance data for fan or pump power consumption at r_N=1.

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.

The function allows r_N to be zero.

Interface

function pressure
  extends Modelica.Icons.Function;
  input Modelica.Units.SI.VolumeFlowRate V_flow "Volumetric flow rate";
  input Real r_N(unit = "1") "Relative revolution, r_N=N/N_nominal";
  input Real d[:] "Derivatives of flow rate vs. pressure at the support points";
  input Modelica.Units.SI.PressureDifference dpMax(displayUnit = "Pa") "Maximum pressure drop at nominal speed, for regularisation";
  input Modelica.Units.SI.VolumeFlowRate V_flow_max "Maximum flow rate at nominal speed, for regularisation";
  input Buildings.Fluid.Movers.BaseClasses.Characteristics.flowParametersInternal per "Pressure performance data";
  output Modelica.Units.SI.PressureDifference dp(displayUnit = "Pa") "Pressure raise";
end pressure;

Revisions

• September 8, 2016, by Michael Wetter and Filip Jorissen:
  Changed implementation to allow r_N = 0.
  This is for #458.
• September 7, 2016, by Michael Wetter:
  Moved function which was a protected function to make it public, as it is now called by Buildings.Fluid.Movers.BaseClasses.FlowMachineInterface.