WaterProps.h

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/**
 *  @file WaterProps.h
 *   Header for a class used to house several approximation
 *   routines for properties of water.
 *  (see \ref thermoprops
 *   and class \link Cantera::WaterProps WaterProps\endlink).
 */
/*
 * Copyright (2006) Sandia Corporation. Under the terms of
 * Contract DE-AC04-94AL85000 with Sandia Corporation, the
 * U.S. Government retains certain rights in this software.
 */
#ifndef CT_WATERPROPS_H
#define CT_WATERPROPS_H


#include "cantera/base/ct_defs.h"
namespace Cantera
{
class WaterPropsIAPWS;
class PDSS_Water;

/**
 * @defgroup relatedProps Electric Properties of Phases
 *
 * <H3> Treatment of the %Phase Potential and the electrochemical potential of
 * a species </H3>
 *
 * The electrochemical potential of species *k* in a phase *p*, \f$ \zeta_k \f$,
 * is related to the chemical potential via the following equation,
 *
 *       \f[
 *            \zeta_{k}(T,P) = \mu_{k}(T,P) + z_k \phi_p
 *       \f]
 *
 * where  \f$ \nu_k \f$ is the charge of species *k*, and \f$ \phi_p \f$ is
 * the electric potential of phase *p*.
 *
 * The potential  \f$ \phi_p \f$ is tracked and internally stored within the
 * base ThermoPhase object. It constitutes a specification of the internal
 * state of the phase; it's the third state variable, the first two being
 * temperature and density (or, pressure, for incompressible equations of
 * state). It may be set with the function,
 * ThermoPhase::setElectricPotential(), and may be queried with the function
 * ThermoPhase::electricPotential().
 *
 * Note, the overall electrochemical potential of a phase may not be changed
 * by the potential because many phases enforce charge neutrality:
 *
 *       \f[
 *            0 = \sum_k z_k X_k
 *       \f]
 *
 * Whether charge neutrality is necessary for a phase is also specified within
 * the ThermoPhase object, by the function call
 * ThermoPhase::chargeNeutralityNecessary(). Note, that it is not necessary
 * for the IdealGas phase, currently. However, it is necessary for liquid
 * phases such as Cantera::DebyeHuckel and Cantera::HMWSoln for the proper
 * specification of the chemical potentials.
 *
 * This equation, when applied to the \f$ \zeta_k \f$ equation described
 * above, results in a zero net change in the effective Gibbs free energy of
 * the phase. However, specific charged species in the phase may increase or
 * decrease their electrochemical potentials, which will have an effect on
 * interfacial reactions involving charged species, when there is a potential
 * drop between phases. This effect is used within the
 * Cantera::InterfaceKinetics and Cantera::EdgeKinetics kinetics objects
 * classes.
 *
 * <H3> Electrothermochemical Properties of Phases of Matter. </H3>
 *
 * The following classes are used to compute the electrical and
 * electrothermochemical properties of phases of matter. The main property
 * currently is the dielectric constant, which is an important parameter for
 * electrolyte solutions. The class WaterProps calculate the dielectric
 * constant of water as a function of temperature and pressure.
 *
 * WaterProps also calculate the constant A_debye used in the Debye Huckel and
 * Pitzer activity coefficient calculations.
 *
 * @ingroup phases
 */
//@{

//! The WaterProps class is used to house several approximation routines for
//! properties of 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 house routine for the calculation
 *  of the dielectric constant of water
 *
 * Most if not all of the member functions are static.
 */
class WaterProps
{
public:
    //! Default constructor
    WaterProps();

    //! Constructor
    /*!
     * @param wptr Pointer to WaterPropsIAPWS object
     */
    WaterProps(WaterPropsIAPWS* wptr);

    //! Constructor with pointer to Water PDSS object
    /*!
     * @param wptr Pointer to water standard state object
     */
    WaterProps(PDSS_Water* wptr);

    //! Copy Constructor
    WaterProps(const WaterProps& b);

    //! destructor
    virtual ~WaterProps();

    //! Assignment operator
    WaterProps& operator=(const WaterProps& b);

    //! 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.
     *
     * @param T temperature in kelvin
     * @param P Pressure in pascal
     * @param ifunc changes what's returned
     *
     * @return 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.
     */
    static doublereal density_T(doublereal T, doublereal P, int ifunc);

    //! 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
     *
     * @param T temperature (kelvin)
     * @param P_pascal pressure in pascal
     * @param ifunc changes what's returned from the function
     *
     * @return 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
     */
    doublereal relEpsilon(doublereal T, doublereal P_pascal,  int ifunc = 0);

    //! 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).
     *
     *    \f[
     *      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}}
     *    \f]
     *
     *  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
     *
     *  @param T  Temperature (kelvin)
     *  @param P  pressure (pascal)
     *  @param ifunc Changes what's returned from the routine
     *
     * @return Returns a single doublereal 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)
     */
    doublereal ADebye(doublereal T, doublereal P, int ifunc);

    //! Returns the saturation pressure given the temperature
    /*!
     * @param T temperature (kelvin)
     * @return returns the saturation pressure (pascal)
     */
    doublereal satPressure(doublereal T);

    //! Returns the density of water
    /*!
     * This function sets the internal temperature and pressure
     * of the underlying object at the same time.
     *
     * @param T Temperature (kelvin)
     * @param P pressure (pascal)
     */
    doublereal density_IAPWS(doublereal T, doublereal P);

    //! Returns the density of water
    /*!
     *  This function uses the internal state of the
     *  underlying water object
     */
    doublereal density_IAPWS() const;

    //! returns the coefficient of thermal expansion
    /*!
     *  @param T Temperature (kelvin)
     *  @param P pressure (pascal)
     */
    doublereal coeffThermalExp_IAPWS(doublereal T, doublereal P);

    //! Returns the isothermal compressibility of water
    /*!
     * @param T  temperature in kelvin
     * @param P  pressure in pascal
     */
    doublereal isothermalCompressibility_IAPWS(doublereal T, doublereal P);

    //! Returns the viscosity of water at the current conditions
    //! (kg/m/s)
    /*!
     *  This function calculates the value of the viscosity of pure
     *  water at the current T and P.
     *
     *  The formulas used are from the paper
     *     J. V. Sengers, J. T. R. Watson, "Improved International
     *     Formulations for the Viscosity and Thermal Conductivity of
     *     Water Substance", J. Phys. Chem. Ref. Data, 15, 1291 (1986).
     *
     *  The formulation is accurate for all temperatures and pressures,
     *  for steam and for water, even near the critical point.
     *  Pressures above 500 MPa and temperature above 900 C are suspect.
     */
    doublereal viscosityWater() const;

    //! Returns the thermal conductivity of water at the current conditions
    //! (W/m/K)
    /*!
     *  This function calculates the value of the thermal conductivity of
     *  water at the current T and P.
     *
     *  The formulas used are from the paper
     *     J. V. Sengers, J. T. R. Watson, "Improved International
     *     Formulations for the Viscosity and Thermal Conductivity of
     *     Water Substance", J. Phys. Chem. Ref. Data, 15, 1291 (1986).
     *
     *  The formulation is accurate for all temperatures and pressures,
     *  for steam and for water, even near the critical point.
     *  Pressures above 500 MPa and temperature above 900 C are suspect.
     */
    doublereal thermalConductivityWater() const;

protected:
    //! Pointer to the WaterPropsIAPWS object
    WaterPropsIAPWS* m_waterIAPWS;

    //! true if we own the WaterPropsIAPWS object
    bool m_own_sub;
};

//@}
}

#endif