Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BaseClasses

Package with base classes for mathematical functions

Package Content

NameDescription
Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BaseClasses.Bounds Bounds Coefficient data record for properties of perfect gases
Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BaseClasses.der_yorkCalc der_yorkCalc Derivative of cooling tower performance correlation for YorkCalc model


Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BaseClasses.Bounds Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BaseClasses.Bounds

Coefficient data record for properties of perfect gases

Information


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


Extends from Modelica.Icons.Record (Icon for a record).

Modelica definition

record Bounds 
  "Coefficient data record for properties of perfect gases"
  extends Modelica.Icons.Record;
  Modelica.SIunits.Temperature TAirInWB_min 
    "Minimum air inlet wet bulb temperature";
  Modelica.SIunits.Temperature TAirInWB_max 
    "Maximum air inlet wet bulb temperature";
  Modelica.SIunits.Temperature TRan_min "Minimum range temperature";
  Modelica.SIunits.Temperature TRan_max "Minimum range temperature";
  Modelica.SIunits.Temperature TApp_min "Minimum approach temperature";
  Modelica.SIunits.Temperature TApp_max "Minimum approach temperature";
  Modelica.SIunits.MassFraction FRWat_min "Minimum water flow ratio";
  Modelica.SIunits.MassFraction FRWat_max "Maximum water flow ratio";
  Modelica.SIunits.MassFraction liqGasRat_max "Maximum liquid to gas ratio";

end Bounds;

Buildings.Fluid.HeatExchangers.CoolingTowers.Correlations.BaseClasses.der_yorkCalc

Derivative of cooling tower performance correlation for YorkCalc model

Information


Derivative of correlation for approach temperature for YorkCalc cooling tower model with respect to FRWat.

During the initialization of the YorkCalc cooling tower model, FRWat is the independent variable. Providing this derivative avoids Dymola from having to compute the Jacobian numerically.



Inputs

TypeNameDefaultDescription
TemperatureTWB 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]
Realder_FRWat Derivative of ratio actual over design air mass flow ratio
Nominal condition
TemperatureTRan Range temperature (water in - water out) [K]

Outputs

TypeNameDescription
Temperatureder_TAppDerivative of approach temperature with respect to FRWat [K]

Modelica definition

function der_yorkCalc 
  "Derivative of cooling tower performance correlation for YorkCalc model"


  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";
  input Real der_FRWat 
    "Derivative of ratio actual over design air mass flow ratio";

  output Modelica.SIunits.Temperature der_TApp 
    "Derivative of approach temperature with respect to FRWat";

protected 
  Modelica.SIunits.Conversions.NonSIunits.Temperature_degC 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;
  // first term due to chain rule
  der_TApp := 1/FRAir * (
       c[10]  +
       c[11] * TWB_degC +
       c[12] * TWB_degC * TWB_degC +
       c[13] * TRan +
       c[14] * TWB_degC * TRan +
       c[15] * TWB_degC * TWB_degC * TRan +
       c[16] * TRan * TRan +
       c[17] * TWB_degC * TRan * TRan +
       c[18] * TWB_degC * TWB_degC * TRan * TRan +
       c[19] * 2 * liqGasRat +
       c[20] * TWB_degC * 2 * liqGasRat +
       c[21] * TWB_degC * TWB_degC * 2 * liqGasRat +
       c[22] * TRan * 2 * liqGasRat +
       c[23] * TWB_degC * TRan * 2 * liqGasRat +
       c[24] * TWB_degC * TWB_degC * TRan * 2 * liqGasRat +
       c[25] * TRan * TRan * 2 * liqGasRat +
       c[26] * TWB_degC * TRan * TRan * 2 * liqGasRat +
       c[27] * TWB_degC * TWB_degC * TRan * TRan * 2 * liqGasRat);
end der_yorkCalc;

HTML-documentation generated by Dymola Tue Sep 29 08:08:12 2009.