PDSS.h

Go to the documentation of this file.

/**
 *  @file PDSS.h
 *    Declarations for the virtual base class PDSS (pressure dependent standard state)
 *    which handles calculations for a single species in a phase
 *    (see @ref pdssthermo and class @link Cantera::PDSS PDSS@endlink).
 */
 
// This file is part of Cantera. See License.txt in the top-level directory or
// at https://cantera.org/license.txt for license and copyright information.
 
#ifndef CT_PDSS_H
#define CT_PDSS_H
#include "cantera/base/ct_defs.h"
#include "cantera/base/AnyMap.h"
 
namespace Cantera
{
/**
 * @defgroup pdssthermo Species Standard-State Thermodynamic Properties
 *
 * In this module we describe %Cantera's treatment of pressure dependent
 * standard states (PDSS) objects. These are objects that calculate the standard
 * state of a single species that depends on both temperature and pressure.
 *
 * To compute the thermodynamic properties of multicomponent solutions, it is
 * necessary to know something about the thermodynamic properties of the
 * individual species present in the solution. Exactly what sort of species
 * properties are required depends on the thermodynamic model for the solution.
 * For a gaseous solution (that is, a gas mixture), the species properties required
 * are usually ideal gas properties at the mixture temperature and at a
 * reference pressure (almost always at 1 bar). For other types of solutions,
 * however, it may not be possible to isolate the species in a "pure" state. For
 * example, the thermodynamic properties of, say, Na+ and Cl- in saltwater are
 * not easily determined from data on the properties of solid NaCl, or solid Na
 * metal, or chlorine gas. In this case, the solvation in water is fundamental
 * to the identity of the species, and some other reference state must be used.
 * One common convention for liquid solutions is to use thermodynamic data for
 * the solutes in the limit of infinite dilution within the pure solvent;
 * another convention is to reference all properties to unit molality.
 *
 * In defining these standard states for species in a phase, we make the
 * following definition. A reference state is a standard state of a species in a
 * phase limited to one particular pressure, the reference pressure. The
 * reference state specifies the dependence of all thermodynamic functions as a
 * function of the temperature, in between a minimum temperature and a maximum
 * temperature. The reference state also specifies the molar volume of the
 * species as a function of temperature. The molar volume is a thermodynamic
 * function. A full standard state does the same thing as a reference state, but
 * specifies the thermodynamics functions at all pressures.
 *
 * Class PDSS is the base class for a family of classes that compute properties
 * of a single species in a phase at its standard states, for a range of
 * temperatures and pressures. PDSS objects are used by derivatives of the
 * VPStandardState class. These classes assume that there exists a standard
 * state for each species in the phase, where the thermodynamic functions are
 * specified as a function of temperature and pressure.  Standard state objects
 * for each species in the phase are all derived from the PDSS virtual base
 * class.
 *
 * The following classes inherit from PDSS. Each of these classes handles just
 * one species.
 *
 * - PDSS_ConstVol
 *    - standardState model = "ConstVol" or "constant_incompressible"
 *    - This model assumes that the species in the phase obeys the constant
 *      partial molar volume pressure dependence. The manager uses a
 *      SpeciesThermoInterpType object to handle the calculation of the reference state.
 *      This object adds the pressure dependencies to these thermo functions.
 *
 * - PDSS_SSVol
 *   - standardState model = "temperature_polynomial"
 *   - standardState model = "density_temperature_polynomial"
 *   - This model assumes that the species in the phase obey a fairly general
 *     equation of state, but one that separates out the calculation of the
 *     standard state density and/or volume. Models include a cubic polynomial
 *     in temperature for either the standard state volume or the standard state
 *     density. The manager uses a SpeciesThermoInterpType object to handle the
 *     calculation of the reference state. This object then adds the pressure
 *     dependencies and the volume terms to these thermo functions to complete the
 *     representation.
 *
 * - PDSS_Water
 *   - standardState model = "Water"
 *   - This model assumes that Species 0 is assumed to be water, and a real
 *     equation of state is used to model the T, P behavior. Note, the model
 *     assumes that the species is liquid water, and not steam.
 *
 * - PDSS_HKFT
 *   - standardState model = "HKFT"
 *   - This model assumes that the species follows the HKFT pressure dependent
 *     equation of state
 *
 * Normally the PDSS object is not called directly. Instead the
 * VPStandardStateTP object manages the calls to the PDSS object for the entire
 * set of species that comprise a phase.
 *
 * The PDSS objects may or may not utilize a SpeciesThermoInterpType reference
 * state manager class to calculate the reference state thermodynamics functions
 * in their own calculation. There are some classes, such as PDSS_IdealGas and
 * PDSS_ConstVol, which utilize the SpeciesThermoInterpType object because the
 * calculation is very similar to the reference state calculation, while there
 * are other classes, PDSS_Water and PDSS_HKFT, which don't utilize the
 * reference state calculation at all, because it wouldn't make sense to. For
 * example, using the PDSS_Water module, there isn't anything special about the
 * reference pressure of 1 bar, so the reference state calculation would
 * represent a duplication of work. Additionally, when evaluating thermodynamic
 * properties at higher pressures and temperatures, near the critical point,
 * evaluation of the thermodynamics at a pressure of 1 bar may lead to
 * situations where the liquid is unstable, that is, beyond the spinodal curve
 * leading to potentially wrong evaluation results.
 *
 * @ingroup thermoprops
 */
 
class SpeciesThermoInterpType;
class VPStandardStateTP;
 
//! Virtual base class for a species with a pressure dependent standard state
/*!
 * Virtual base class for calculation of the pressure dependent standard state
 * for a single species
 *
 * Class PDSS is the base class for a family of classes that compute properties
 * of a set of species in their standard states at a range of temperatures and
 * pressures. The independent variables for this object are temperature and
 * pressure. The class may have a reference to a SpeciesThermoInterpType object
 * which handles the calculation of the reference state temperature behavior of
 * the species.
 *
 * This class is analogous to the SpeciesThermoInterpType class, except that
 * the standard state inherently incorporates the pressure dependence.
 *
 * The class operates on a setState temperature and pressure basis. It only
 * recalculates the standard state when the setState functions for temperature
 * and pressure are called.
 *
 * @ingroup pdssthermo
 */
class PDSS
{
public:
    //! @name Constructors
    //! @{
 
    //! Default Constructor
    PDSS() = default;
 
    // PDSS objects are not copyable or assignable
    PDSS(const PDSS& b) = delete;
    PDSS& operator=(const PDSS& b) = delete;
    virtual ~PDSS() = default;
 
    //! @}
    //! @name Molar Thermodynamic Properties of the Species Standard State
    //! @{
 
    //! Return the molar enthalpy in units of J kmol-1
    /*!
     * @return the species standard state enthalpy in J kmol-1 at the current
     *     temperature and pressure.
     */
    virtual double enthalpy_mole() const;
 
    //! Return the standard state molar enthalpy divided by RT
    /*!
     * @return The dimensionless species standard state enthalpy divided at
     *     the current temperature and pressure.
     */
    virtual double enthalpy_RT() const;
 
    //! Return the molar internal Energy in units of J kmol-1
    /*!
     * @return The species standard state internal Energy in J kmol-1 at the
     *     current temperature and pressure.
     */
    virtual double intEnergy_mole() const;
 
    //! Return the molar entropy in units of J kmol-1 K-1
    /*!
     * @return The species standard state entropy in J kmol-1 K-1 at the
     *     current temperature and pressure.
     */
    virtual double entropy_mole() const;
 
    //! Return the standard state entropy divided by RT
    /*!
     * @return The species standard state entropy divided by RT at the current
     *     temperature and pressure.
     */
    virtual double entropy_R() const;
 
    //! Return the molar Gibbs free energy in units of J kmol-1
    /*!
     * @return The species standard state Gibbs free energy in J kmol-1 at the
     * current temperature and pressure.
     */
    virtual double gibbs_mole() const;
 
    //! Return the molar Gibbs free energy divided by RT
    /*!
     * @return The species standard state Gibbs free energy divided by RT at
     *     the current temperature and pressure.
     */
    virtual double gibbs_RT() const;
 
    //! Return the molar const pressure heat capacity in units of J kmol-1 K-1
    /*!
     * @return The species standard state Cp in J kmol-1 K-1 at the current
     *     temperature and pressure.
     */
    virtual double cp_mole() const;
 
    //! Return the molar const pressure heat capacity divided by RT
    /*!
     * @return The species standard state Cp divided by RT at the current
     *     temperature and pressure.
     */
    virtual double cp_R() const;
 
    //! Return the molar const volume heat capacity in units of J kmol-1 K-1
    /*!
     * @return The species standard state Cv in J kmol-1 K-1 at the
     * current temperature and pressure.
     */
    virtual double cv_mole() const;
 
    //! Return the molar volume at standard state
    /*!
     * @return The standard state molar volume at the current temperature and
     *     pressure. Units are m**3 kmol-1.
     */
    virtual double molarVolume() const;
 
    //! Return the temperature derivative of the standard state molar volume
    //! at constant pressure [m³/kmol/K].
    //!
    //! @return @f$ (dV^\circ/dT)_P @f$ at the current temperature and pressure.
    //! @since New in %Cantera 4.0.
    virtual double dVdT() const;
 
    //! Return the pressure derivative of the standard state molar volume
    //! at constant temperature [m³/kmol/Pa].
    //!
    //! @return @f$ (dV^\circ/dP)_T @f$ at the current temperature and pressure.
    //! @since New in %Cantera 4.0.
    virtual double dVdP() const;
 
    //! Return the standard state density at standard state
    /*!
     * @return The standard state density at the current temperature and
     *     pressure. units are kg m-3
     */
    virtual double density() const;
 
    //! @}
    //! @name Properties of the Reference State of the Species in the Solution
    //! @{
 
    //! Return the reference pressure for this phase.
    double refPressure() const {
        return m_p0;
    }
 
    //! return the minimum temperature
    double minTemp() const {
        return m_minTemp;
    }
 
    //! return the minimum temperature
    double maxTemp() const {
        return m_maxTemp;
    }
 
    //! Return the molar Gibbs free energy divided by RT at reference pressure
    /*!
     * @return The reference state Gibbs free energy at the current
     *     temperature, divided by RT.
     */
    virtual double gibbs_RT_ref() const;
 
    //! Return the molar enthalpy divided by RT at reference pressure
    /*!
     * @return The species reference state enthalpy at the current
     *     temperature, divided by RT.
     */
    virtual double enthalpy_RT_ref() const;
 
    //! Return the molar entropy divided by R at reference pressure
    /*!
     * @return The species reference state entropy at the current
     *     temperature, divided by R.
     */
    virtual double entropy_R_ref() const;
 
    //! Return the molar heat capacity divided by R at reference pressure
    /*!
     * @return The species reference state heat capacity divided by R at the
     * current temperature.
     */
    virtual double cp_R_ref() const;
 
    //! Return the molar volume at reference pressure
    /*!
     * @return The reference state molar volume. units are m**3 kmol-1.
     */
    virtual double molarVolume_ref() const;
 
    //! @}
    //! @name Mechanical Equation of State Properties
    //! @{
 
    //! Returns the pressure (Pa)
    virtual double pressure() const;
 
    //! Sets the pressure in the object
    /*!
     * Currently, this sets the pressure in the PDSS object. It is indeterminant
     * what happens to the owning VPStandardStateTP object.
     *
     * @param   pres   Pressure to be set (Pascal)
     */
    virtual void setPressure(double pres);
 
    //! Return the volumetric thermal expansion coefficient. Units: 1/K.
    /*!
     * The thermal expansion coefficient is defined as
     * @f[
     *     \beta = \frac{1}{v}\left(\frac{\partial v}{\partial T}\right)_P
     * @f]
     */
    virtual double thermalExpansionCoeff() const;
    //! @}
 
    //! Set the internal temperature
    /*!
     * @param temp Temperature (Kelvin)
     */
    virtual void setTemperature(double temp);
 
    //! Return the current stored temperature
    virtual double temperature() const;
 
    //! Set the internal temperature and pressure
    /*!
     * @param  temp     Temperature (Kelvin)
     * @param  pres     pressure (Pascals)
     */
    virtual void setState_TP(double temp, double pres);
 
    //! critical temperature
    virtual double critTemperature() const;
 
    //! critical pressure
    virtual double critPressure() const;
 
    //! critical density
    virtual double critDensity() const;
 
    //! saturation pressure
    /*!
     *  @param T Temperature (Kelvin)
     */
    virtual double satPressure(double T);
 
    //! Return the molecular weight of the species
    //! in units of kg kmol-1
    double molecularWeight() const;
 
    //! Set the molecular weight of the species
    /*!
     * @param mw Molecular Weight in kg kmol-1
     */
    void setMolecularWeight(double mw);
 
    //! @name Initialization of the Object
    //! @{
 
    //! Set the SpeciesThermoInterpType object used to calculate reference
    //! state properties
    void setReferenceThermo(shared_ptr<SpeciesThermoInterpType> stit) {
        m_spthermo = stit;
    }
 
    //! Set the parent VPStandardStateTP object of this PDSS object
    /*!
     * This information is only used by certain PDSS subclasses
     * @param phase   Pointer to the parent phase
     * @param k       Index of this species in the phase
     */
    virtual void setParent(VPStandardStateTP* phase, size_t k) {}
 
    //! Initialization routine
    /*!
     * This is a cascading call, where each level should call the the parent
     * level.
     */
    virtual void initThermo() {}
 
    //! Set model parameters from an AnyMap phase description, for example from the
    //! `equation-of-state` field of a species definition.
    void setParameters(const AnyMap& node) {
        m_input = node;
    }
 
    //! Store the parameters needed to reconstruct a copy of this PDSS object
    virtual void getParameters(AnyMap& eosNode) const {}
 
    //! @}
 
protected:
    //! Current temperature used by the PDSS object
    mutable double m_temp = -1.0;
 
    //! State of the system - pressure
    mutable double m_pres = -1.0;
 
    //! Reference state pressure of the species.
    double m_p0 = -1.0;
 
    //! Minimum temperature
    double m_minTemp = -1.0;
 
    //! Maximum temperature
    double m_maxTemp = 10000.0;
 
    //! Molecular Weight of the species
    double m_mw = 0.0;
 
    //! Input data supplied via setParameters. This may include parameters for
    //! different phase models, which will be used when initThermo() is called.
    AnyMap m_input;
 
    //! Pointer to the species thermodynamic property manager. Not used in all
    //! PDSS models.
    shared_ptr<SpeciesThermoInterpType> m_spthermo;
};
 
//! Base class for PDSS classes which compute molar properties directly
class PDSS_Molar : public virtual PDSS
{
public:
    double enthalpy_RT() const override;
    double entropy_R() const override;
    double gibbs_RT() const override;
    double cp_R() const override;
};
 
//! Base class for PDSS classes which compute nondimensional properties directly
class PDSS_Nondimensional : public virtual PDSS
{
public:
    PDSS_Nondimensional();
 
    double enthalpy_mole() const override;
    double entropy_mole() const override;
    double gibbs_mole() const override;
    double cp_mole() const override;
 
    double enthalpy_RT_ref() const override;
    double entropy_R_ref() const override;
    double gibbs_RT_ref() const override;
    double cp_R_ref() const override;
    double molarVolume_ref() const override;
    double enthalpy_RT() const override;
    double entropy_R() const override;
    double gibbs_RT() const override;
    double cp_R() const override;
    double molarVolume() const override;
    double density() const override;
 
protected:
    double m_h0_RT; //!< Reference state enthalpy divided by RT
    double m_cp0_R; //!< Reference state heat capacity divided by R
    double m_s0_R; //!< Reference state entropy divided by R
    double m_g0_RT; //!< Reference state Gibbs free energy divided by RT
    double m_V0; //!< Reference state molar volume (m^3/kmol)
    double m_hss_RT; //!< Standard state enthalpy divided by RT
    double m_cpss_R; //!< Standard state heat capacity divided by R
    double m_sss_R; //!< Standard state entropy divided by R
    double m_gss_RT; //!< Standard state Gibbs free energy divided by RT
    double m_Vss; //!< Standard State molar volume (m^3/kmol)
};
 
}
 
#endif