Buildings.HeatExchangers.CoolingTowers.Correlations

Package Content

Name	Description
BaseClasses	Package with base classes for mathematical functions
BoundsYorkCalc	Coefficient data record for properties of perfect gases
Examples	Collection of models that illustrate model use and test models
yorkCalc	Cooling tower performance correlation for YorkCalc model

Buildings.HeatExchangers.CoolingTowers.Correlations.BoundsYorkCalc

Information

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

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 perfect gases" 
  extends 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.HeatExchangers.CoolingTowers.Correlations.yorkCalc

Information

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

Parameters

Type	Name	Default	Description
Nominal condition
Temperature	TRan		Range temperature (water in - water out) [K]

Inputs

Type	Name	Default	Description
Temperature	TWB		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
Temperature	TRan		Range temperature (water in - water out) [K]

Outputs

Type	Name	Description
Temperature	TApp	Approach temperature [K]

Modelica definition

function yorkCalc 
  "Cooling tower performance correlation for YorkCalc model" 
  annotation(derivative=BaseClasses.der_yorkCalc);  
  
  
  input Modelica.SIunits.Temperature TRan 
    "Range temperature (water in - water out)";
  input Modelica.SIunits.Temperature TWB "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.Temperature TApp "Approach temperature";
  
protected 
  Modelica.SIunits.CelsiusTemperature TWB_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 
  TWB_degC :=Modelica.SIunits.Conversions.to_degC(TWB);
  liqGasRat := FRWat/FRAir;
  TApp := c[1] +
       c[2] * TWB_degC +
       c[3] * TWB_degC * TWB_degC +
       c[4] * TRan +
       c[5] * TWB_degC * TRan +
       c[6] * TWB_degC * TWB_degC * TRan +
       c[7] * TRan * TRan +
       c[8] * TWB_degC * TRan * TRan +
       c[9] * TWB_degC * TWB_degC * TRan * TRan +
       c[10] * liqGasRat +
       c[11] * TWB_degC * liqGasRat +
       c[12] * TWB_degC * TWB_degC * liqGasRat +
       c[13] * TRan * liqGasRat +
       c[14] * TWB_degC * TRan * liqGasRat +
       c[15] * TWB_degC * TWB_degC * TRan * liqGasRat +
       c[16] * TRan * TRan * liqGasRat +
       c[17] * TWB_degC * TRan * TRan * liqGasRat +
       c[18] * TWB_degC * TWB_degC * TRan * TRan * liqGasRat +
       c[19] * liqGasRat * liqGasRat +
       c[20] * TWB_degC * liqGasRat * liqGasRat +
       c[21] * TWB_degC * TWB_degC * liqGasRat * liqGasRat +
       c[22] * TRan * liqGasRat * liqGasRat +
       c[23] * TWB_degC * TRan * liqGasRat * liqGasRat +
       c[24] * TWB_degC * TWB_degC * TRan * liqGasRat * liqGasRat +
       c[25] * TRan * TRan * liqGasRat * liqGasRat +
       c[26] * TWB_degC * TRan * TRan * liqGasRat * liqGasRat +
       c[27] * TWB_degC * TWB_degC * TRan * TRan * liqGasRat * liqGasRat;
end yorkCalc;