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Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations

Package with correlations for cooling tower performance

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

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


Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BoundsYorkCalc Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BoundsYorkCalc

Coefficient data record for properties of York cooling tower model

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

TypeNameDefaultDescription
TemperatureTAirInWB_min273.15 - 34.4Minimum air inlet wet bulb temperature [K]
TemperatureTAirInWB_max273.15 + 26.7Maximum air inlet wet bulb temperature [K]
TemperatureTRan_min1.1Minimum range temperature [K]
TemperatureTRan_max22.2Minimum range temperature [K]
TemperatureTApp_min1.1Minimum approach temperature [K]
TemperatureTApp_max40Minimum approach temperature [K]
MassFractionFRWat_min0.75Minimum water flow ratio [1]
MassFractionFRWat_max1.25Maximum water flow ratio [1]
MassFractionliqGasRat_max8Maximum 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

Cooling tower performance correlation for YorkCalc model

Information

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

Inputs

TypeNameDefaultDescription
TemperatureTWetBul Air wet-bulb inlet temperature [K]
MassFractionFRWat Ratio actual over design water mass flow ratio [1]
MassFractionFRAir Ratio actual over design air mass flow ratio [1]
Nominal condition
TemperatureDifferenceTRan Range temperature (water in - water out) [K]

Outputs

TypeNameDescription
TemperatureDifferenceTAppApproach 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;

Automatically generated Wed Feb 22 15:22:14 2012.