Cantera  3.1.0b1
Loading...
Searching...
No Matches
WaterProps Class Reference

The WaterProps class is used to house several approximation routines for properties of water. More...

#include <WaterProps.h>

Detailed Description

The WaterProps class is used to house several approximation routines for properties of water.

This is a helper class for WaterSSTP and PDSS_Water and does not constitute a complete implementation of a thermo phase by itself (see Thermodynamic Properties and classes WaterSSTP and PDSS_Water).

The class is also a wrapper around the WaterPropsIAPWS class which provides the calculations for the equation of state properties for water.

In particular, this class houses methods for the calculation of the dielectric constant of water and the constant A_debye used in the Debye-Huckel and Pitzer activity coefficient calculations.

Definition at line 37 of file WaterProps.h.

Public Member Functions

 WaterProps ()
 Default constructor.
 
 WaterProps (WaterPropsIAPWS *wptr)
 Constructor.
 
 WaterProps (PDSS_Water *wptr)
 Constructor with pointer to Water PDSS object.
 
 WaterProps (const WaterProps &b)=delete
 
WaterPropsoperator= (const WaterProps &b)=delete
 
double relEpsilon (double T, double P_pascal, int ifunc=0)
 Bradley-Pitzer equation for the dielectric constant of water as a function of temperature and pressure.
 
double ADebye (double T, double P, int ifunc)
 ADebye calculates the value of A_Debye as a function of temperature and pressure according to relations that take into account the temperature and pressure dependence of the water density and dielectric constant.
 
double satPressure (double T)
 Returns the saturation pressure given the temperature.
 
double density_IAPWS (double T, double P)
 Returns the density of water.
 
double density_IAPWS () const
 Returns the density of water.
 
double coeffThermalExp_IAPWS (double T, double P)
 returns the coefficient of thermal expansion
 
double isothermalCompressibility_IAPWS (double T, double P)
 Returns the isothermal compressibility of water.
 

Static Public Member Functions

static double density_T (double T, double P, int ifunc)
 Simple calculation of water density at atmospheric pressure.
 

Protected Attributes

WaterPropsIAPWSm_waterIAPWS = nullptr
 Pointer to the WaterPropsIAPWS object.
 
bool m_own_sub = false
 true if we own the WaterPropsIAPWS object
 

Constructor & Destructor Documentation

◆ WaterProps() [1/3]

Default constructor.

Definition at line 14 of file WaterProps.cpp.

◆ WaterProps() [2/3]

Constructor.

Parameters
wptrPointer to WaterPropsIAPWS object

Definition at line 31 of file WaterProps.cpp.

◆ WaterProps() [3/3]

WaterProps ( PDSS_Water wptr)

Constructor with pointer to Water PDSS object.

Parameters
wptrPointer to water standard state object

Definition at line 20 of file WaterProps.cpp.

◆ ~WaterProps()

~WaterProps ( )
virtual

Definition at line 41 of file WaterProps.cpp.

Member Function Documentation

◆ density_T()

double density_T ( double  T,
double  P,
int  ifunc 
)
static

Simple calculation of water density at atmospheric pressure.

Valid up to boiling point.

This formulation has no dependence on the pressure and shouldn't be used where accuracy is needed.

Parameters
Ttemperature in kelvin
PPressure in pascal
ifuncchanges what's returned
Returns
value returned depends on ifunc value:
  • ifunc = 0 Returns the density in kg/m^3
  • ifunc = 1 returns the derivative of the density wrt T.
  • ifunc = 2 returns the 2nd derivative of the density wrt T
  • ifunc = 3 returns the derivative of the density wrt P.

Verification: Agrees with the CRC values (6-10) for up to 4 sig digits.

units = returns density in kg m-3.

Definition at line 48 of file WaterProps.cpp.

◆ relEpsilon()

double relEpsilon ( double  T,
double  P_pascal,
int  ifunc = 0 
)

Bradley-Pitzer equation for the dielectric constant of water as a function of temperature and pressure.

Returns the dimensionless relative dielectric constant and its derivatives.

Range of validity: 0 to 350C, 0 to 1 kbar pressure

Parameters
Ttemperature (kelvin)
P_pascalpressure in pascal
ifuncchanges what's returned from the function
Returns
Depends on the value of ifunc:
  • ifunc = 0 return value
  • ifunc = 1 return temperature derivative
  • ifunc = 2 return temperature second derivative
  • ifunc = 3 return pressure first derivative

Validation: Numerical experiments indicate that this function agrees with the Archer and Wang data in the CRC p. 6-10 to all 4 significant digits shown (0 to 100C).

value at 25C and 1 atm, relEps = 78.38

Definition at line 96 of file WaterProps.cpp.

◆ ADebye()

double ADebye ( double  T,
double  P,
int  ifunc 
)

ADebye calculates the value of A_Debye as a function of temperature and pressure according to relations that take into account the temperature and pressure dependence of the water density and dielectric constant.

The A_Debye expression appears on the top of the ln actCoeff term in the general Debye-Huckel expression It depends on temperature and pressure. And, therefore, most be recalculated whenever T or P changes. The units returned by this expression are sqrt(kg/gmol).

\[ A_{Debye} = \frac{1}{8 \pi} \sqrt{\frac{2 N_{Avog} \rho_w}{1000}} {\left(\frac{e^2}{\epsilon k_{boltz} T}\right)}^{\frac{3}{2}} \]

Nominal value at 25C and 1atm = 1.172576 sqrt(kg/gmol).

Based on:

  • epsilon/epsilon_0 = 78.54 (water at 25C)
  • T = 298.15 K
  • B_Debye = 3.28640E9 sqrt(kg/gmol)/m
Parameters
TTemperature (kelvin)
Ppressure (pascal)
ifuncChanges what's returned from the routine
Returns
a double whose meaning depends on ifunc:
  • ifunc = 0 return value
  • ifunc = 1 return temperature derivative
  • ifunc = 2 return temperature second derivative
  • ifunc = 3 return pressure first derivative

Verification: With the epsRelWater value from the Bradley-Pitzer relation, and the water density from the density_IAPWS() function, The A_Debye computed with this function agrees with the Pitzer table p. 99 to 4 significant digits at 25C. and 20C. (Aphi = ADebye/3)

Definition at line 147 of file WaterProps.cpp.

◆ satPressure()

double satPressure ( double  T)

Returns the saturation pressure given the temperature.

Parameters
Ttemperature (kelvin)
Returns
the saturation pressure (pascal)

Definition at line 220 of file WaterProps.cpp.

◆ density_IAPWS() [1/2]

double density_IAPWS ( double  T,
double  P 
)

Returns the density of water.

This function sets the internal temperature and pressure of the underlying object at the same time.

Parameters
TTemperature (kelvin)
Ppressure (pascal)

Definition at line 225 of file WaterProps.cpp.

◆ density_IAPWS() [2/2]

double density_IAPWS ( ) const

Returns the density of water.

This function uses the internal state of the underlying water object

Definition at line 230 of file WaterProps.cpp.

◆ coeffThermalExp_IAPWS()

double coeffThermalExp_IAPWS ( double  T,
double  P 
)

returns the coefficient of thermal expansion

Parameters
TTemperature (kelvin)
Ppressure (pascal)

Definition at line 235 of file WaterProps.cpp.

◆ isothermalCompressibility_IAPWS()

double isothermalCompressibility_IAPWS ( double  T,
double  P 
)

Returns the isothermal compressibility of water.

Parameters
Ttemperature in kelvin
Ppressure in pascal

Definition at line 245 of file WaterProps.cpp.

Member Data Documentation

◆ m_waterIAPWS

WaterPropsIAPWS* m_waterIAPWS = nullptr
protected

Pointer to the WaterPropsIAPWS object.

Definition at line 184 of file WaterProps.h.

◆ m_own_sub

bool m_own_sub = false
protected

true if we own the WaterPropsIAPWS object

Definition at line 187 of file WaterProps.h.


The documentation for this class was generated from the following files: