Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations

Information

This package contains the performance curve for the Buildings.Fluid.HeatExchangers.CoolingTowers.YorkCalc cooling tower model.

Extends from Modelica.Icons.MaterialProperty (Icon for property classes).

Package Content

Name	Description
BoundsYorkCalc	Coefficient data record for properties of York cooling tower model
yorkCalc	Cooling tower performance correlation for YorkCalc model
Examples	Collection of models that illustrate model use and test models
BaseClasses	Package with base classes for Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations

Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BoundsYorkCalc

Information

This data record contains the bounds for the YorkCalc cooling tower correlations.

Extends from Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BaseClasses.Bounds (Coefficient data record for properties of cooling tower model).

Parameters

Type	Name	Default	Description
Temperature	TAirInWB_min	273.15 - 34.4	Minimum air inlet wet bulb temperature [K]
Temperature	TAirInWB_max	273.15 + 26.7	Maximum air inlet wet bulb temperature [K]
Temperature	TRan_min	1.1	Minimum range temperature [K]
Temperature	TRan_max	22.2	Minimum range temperature [K]
Temperature	TApp_min	1.1	Minimum approach temperature [K]
Temperature	TApp_max	40	Minimum approach temperature [K]
MassFraction	FRWat_min	0.75	Minimum water flow ratio [1]
MassFraction	FRWat_max	1.25	Maximum water flow ratio [1]
MassFraction	liqGasRat_max	8	Maximum liquid to gas ratio [1]

Modelica definition

record BoundsYorkCalc 
  "Coefficient data record for properties of York cooling tower model"
  extends Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BaseClasses.Bounds
    (TAirInWB_min = 273.15-34.4,
     TAirInWB_max = 273.15+26.7,
     TRan_min =     1.1,
     TRan_max =     22.2,
     TApp_min =     1.1,
     TApp_max =     40,
     FRWat_min =     0.75,
     FRWat_max =    1.25,
     liqGasRat_max = 8);

end BoundsYorkCalc;

Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.yorkCalc

Information

Correlation for approach temperature for YorkCalc cooling tower model. See Examples/YorkCalc.mo for the graph.

Inputs

Type	Name	Default	Description
Temperature	TWetBul		Air wet-bulb inlet temperature [K]
MassFraction	FRWat		Ratio actual over design water mass flow ratio [1]
MassFraction	FRAir		Ratio actual over design air mass flow ratio [1]
Nominal condition
TemperatureDifference	TRan		Range temperature (water in - water out) [K]

Outputs

Type	Name	Description
TemperatureDifference	TApp	Approach temperature [K]

Modelica definition

function yorkCalc 
  "Cooling tower performance correlation for YorkCalc model"

  input Modelica.SIunits.TemperatureDifference TRan 
    "Range temperature (water in - water out)";
  input Modelica.SIunits.Temperature TWetBul "Air wet-bulb inlet temperature";
  input Modelica.SIunits.MassFraction FRWat 
    "Ratio actual over design water mass flow ratio";
  input Modelica.SIunits.MassFraction FRAir 
    "Ratio actual over design air mass flow ratio";

  output Modelica.SIunits.TemperatureDifference TApp "Approach temperature";

protected 
  Modelica.SIunits.Conversions.NonSIunits.Temperature_degC TWetBul_degC 
    "Air wet-bulb inlet temperature";
  Modelica.SIunits.MassFraction liqGasRat "Liquid to gas mass flow ratio";
  constant Real c[:] = {-0.359741205, -0.055053608,  0.0023850432,
                      0.173926877, -0.0248473764,  0.00048430224,
                      -0.005589849456,  0.0005770079712, -0.00001342427256,
                      2.84765801111111, -0.121765149,  0.0014599242,
                      1.680428651, -0.0166920786, -0.0007190532,
                     -0.025485194448,  0.0000487491696,  0.00002719234152,
                     -0.0653766255555556, -0.002278167,  0.0002500254,
                     -0.0910565458,  0.00318176316,  0.000038621772,
                     -0.0034285382352,  0.00000856589904, -0.000001516821552} 
    "Polynomial coefficients";

algorithm 
  TWetBul_degC :=Modelica.SIunits.Conversions.to_degC(TWetBul);
  // smoothMax is added to the numerator and denominator so that
  // liqGasRat -> 1, as both FRWat -> 0 and FRAir -> 0
  liqGasRat := Buildings.Utilities.Math.Functions.smoothMax(x1=1E-4, x2=FRWat, deltaX=1E-5)/
               Buildings.Utilities.Math.Functions.smoothMax(x1=1E-4, x2=FRAir, deltaX=1E-5);
  TApp := c[1] +
       c[2] * TWetBul_degC +
       c[3] * TWetBul_degC * TWetBul_degC +
       c[4] * TRan +
       c[5] * TWetBul_degC * TRan +
       c[6] * TWetBul_degC * TWetBul_degC * TRan +
       c[7] * TRan * TRan +
       c[8] * TWetBul_degC * TRan * TRan +
       c[9] * TWetBul_degC * TWetBul_degC * TRan * TRan +
       c[10] * liqGasRat +
       c[11] * TWetBul_degC * liqGasRat +
       c[12] * TWetBul_degC * TWetBul_degC * liqGasRat +
       c[13] * TRan * liqGasRat +
       c[14] * TWetBul_degC * TRan * liqGasRat +
       c[15] * TWetBul_degC * TWetBul_degC * TRan * liqGasRat +
       c[16] * TRan * TRan * liqGasRat +
       c[17] * TWetBul_degC * TRan * TRan * liqGasRat +
       c[18] * TWetBul_degC * TWetBul_degC * TRan * TRan * liqGasRat +
       c[19] * liqGasRat * liqGasRat +
       c[20] * TWetBul_degC * liqGasRat * liqGasRat +
       c[21] * TWetBul_degC * TWetBul_degC * liqGasRat * liqGasRat +
       c[22] * TRan * liqGasRat * liqGasRat +
       c[23] * TWetBul_degC * TRan * liqGasRat * liqGasRat +
       c[24] * TWetBul_degC * TWetBul_degC * TRan * liqGasRat * liqGasRat +
       c[25] * TRan * TRan * liqGasRat * liqGasRat +
       c[26] * TWetBul_degC * TRan * TRan * liqGasRat * liqGasRat +
       c[27] * TWetBul_degC * TWetBul_degC * TRan * TRan * liqGasRat * liqGasRat;
end yorkCalc;