Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.Functions

Information

This package contains functions that are used in Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.

Extends from Modelica.Icons.BasesPackage (Icon for packages containing base classes).

Package Content

Name	Description
speedShift	Interpolates value between two speeds
warnIfPerformanceOutOfBounds	Function that checks the performance and writes a warning if it is outside of 0.9 to 1.1

Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.Functions.speedShift

Information

This function interpolates data for intermediate compressor speeds using cubic hermite splines with linear extrapolation. To avoid linear extrapolation below minimum standard speed, the origin is added to the modified arrays.

Inputs

Type	Name	Default	Description
Real	spe		Speed of compressor
Real	speSet[:]		Array of standard compressor speeds
Real	u[:]		Array to be interpolated

Outputs

Type	Name	Description
Real	y	Interpolated value

Modelica definition

function speedShift "Interpolates value between two speeds"
  //x in cubic Hermite function
  input Real spe "Speed of compressor";
  //x1, x2  in cubic Hermite function
  input Real speSet[:] "Array of standard compressor speeds";
  //y1, y2 in cubic Hermite function
  input Real u[:] "Array to be interpolated";
  output Real y "Interpolated value";
protected 
  Integer n= size(u,1)+1 "Number of elements in modified array";
  Real derv[n] "deriative";
  Integer i=1 "Integer to select data interval";
  Real modSpeSet[n] "Speed set with origin";
  Real modU[n];
algorithm 
    //y1d, y2d in cubic Hermite function
    modSpeSet:= cat(1, {0.00}, speSet);
    modU     := cat(1, {0.00}, u);
    derv     := Buildings.Utilities.Math.Functions.splineDerivatives(
                   x=modSpeSet,
                   y=modU) "derivatives at standard speeds";
    //locate the range between which compressor operates
    for j in 1:size(modSpeSet, 1) - 1 loop
      if spe > modSpeSet[j] then
        i :=j;
      end if;
    end for;
    y :=Buildings.Utilities.Math.Functions.cubicHermiteLinearExtrapolation(
      x=spe,
      x1=modSpeSet[i],
      x2=modSpeSet[i + 1],
      y1=modU[i],
      y2=modU[i + 1],
      y1d=derv[i],
      y2d=derv[i + 1]);
end speedShift;

Buildings.Fluid.HeatExchangers.DXCoils.BaseClasses.Functions.warnIfPerformanceOutOfBounds

Information

Inputs

Type	Name	Default	Description
Real	x		Argument to be checked
String	msg		String to be added to warning message
String	curveName		Name of the curve that was tested

Outputs

Type	Name	Description
Integer	retVal	0 if x is inside bounds, -1 if it is below bounds, or +1 if it is above bounds

Modelica definition

function warnIfPerformanceOutOfBounds 
  "Function that checks the performance and writes a warning if it is outside of 0.9 to 1.1"
  input Real x "Argument to be checked";
  input String msg "String to be added to warning message";
  input String curveName "Name of the curve that was tested";
  output Integer retVal 
    "0 if x is inside bounds, -1 if it is below bounds, or +1 if it is above bounds";

algorithm 
  if (x > 1.1) then
    retVal :=1;
  elseif ( x < 0.9) then
      retVal :=-1;
  else
    retVal :=0;
  end if;
  if (retVal <> 0) then
      Modelica.Utilities.Streams.print("************************************************************************************");
      Modelica.Utilities.Streams.print("*** Warning: DX coil performance curves at nominal conditions are outside of bounds.");
      Modelica.Utilities.Streams.print(msg + " is outside of bounds 0.9 to 1.1.");
      Modelica.Utilities.Streams.print("The value of the curve fit is " + String(x));
      Modelica.Utilities.Streams.print("Check the coefficients of the function " + curveName);
      Modelica.Utilities.Streams.print("************************************************************************************");

  end if;

end warnIfPerformanceOutOfBounds;