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Changed the definition of the reference state of pure fluids.

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The reference state for pure fluids is defined as an ideal gas at the
current temperature of the fluid at the reference pressure.
It was defined as the real fluid properties at the current temperature
and the reference pressure. However, this definition doesn't allow
for the easy calculation of fugacities. 

Added some documentation, also, concerning the standard state
definition.
This commit is contained in:
Harry Moffat 2011-07-23 19:39:08 +00:00
parent ff7e66e5a3
commit f7d87724ae
2 changed files with 23 additions and 12 deletions
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11
Cantera/src/thermo/PureFluidPhase.cpp
View file

@ -355,7 +355,8 @@ namespace Cantera {
double psave = pressure();
double t = temperature();
double pref = m_spthermo->refPressure();
Set(tpx::TP, t, pref);
double plow = 1.0E-8;
Set(tpx::TP, t, plow);
getEnthalpy_RT(hrt);
Set(tpx::TP, t, psave);
@ -371,8 +372,10 @@ namespace Cantera {
double psave = pressure();
double t = temperature();
double pref = m_spthermo->refPressure();
Set(tpx::TP, t, pref);
double plow = 1.0E-8;
Set(tpx::TP, t, plow);
getGibbs_RT(grt);
grt[0] += log(pref/plow);
Set(tpx::TP, t, psave);
}
//====================================================================================================================
@ -399,8 +402,10 @@ namespace Cantera {
double psave = pressure();
double t = temperature();
double pref = m_spthermo->refPressure();
Set(tpx::TP, t, pref);
double plow = 1.0E-8;
Set(tpx::TP, t, plow);
getEntropy_R(er);
er[0] -= log(pref/plow);
Set(tpx::TP, t, psave);
}
//====================================================================================================================

24
Cantera/src/thermo/PureFluidPhase.h
View file

@ -304,6 +304,12 @@ namespace Cantera {
//@}
/// @name Properties of the Standard State of the Species in the Solution
/*!
* The standard state of the pure fluid is defined as the real properties
* of the pure fluid at the most stable state of the fluid at the current
* temperature and pressure of the solution. With this definition, the
* activity of the fluid is always then defined to be equal to one.
*/
//@{
//! Get the array of chemical potentials at unit activity for the species
@ -342,15 +348,19 @@ namespace Cantera {
*/
virtual void getGibbs_RT(doublereal* grt) const;
//@}
/// @name Thermodynamic Values for the Species Reference States
/*!
* The species reference state for pure fluids is defined as an ideal gas at the
* reference pressure and current temperature of the fluid.
*/
//@{
//! Returns the vector of nondimensional enthalpies of the reference state at the current temperature
//! of the solution and the reference pressure for the species.
/*!
* This base function will throw a CanteraException unless
* This base function will throw a Cantera exception unless
* it is overwritten in a derived class.
*
* @param hrt Output vector containing the nondimensional reference state enthalpies
@ -358,8 +368,7 @@ namespace Cantera {
*/
virtual void getEnthalpy_RT_ref(doublereal *hrt) const;
//! Returns the vector of nondimensional
//! Gibbs Free Energies of the reference state at the current temperature
//! Returns the vector of nondimensional Gibbs Free Energies of the reference state at the current temperature
//! of the solution and the reference pressure for the species.
/*!
* @param grt Output vector containing the nondimensional reference state
@ -372,15 +381,14 @@ namespace Cantera {
/*!
* units = J/kmol
*
* @param g Output vector containing the reference state
* @param g Output vector containing the reference state
* Gibbs Free energies. Length: m_kk. Units: J/kmol.
*/
virtual void getGibbs_ref(doublereal *g) const;
//! Returns the vector of nondimensional
//! entropies of the reference state at the current temperature
//! Returns the vector of nondimensional entropies of the reference state at the current temperature
//! of the solution and the reference pressure for each species.
/*!
* @param er Output vector containing the nondimensional reference state
@ -388,7 +396,6 @@ namespace Cantera {
*/
virtual void getEntropy_R_ref(doublereal *er) const;
/**
* @name Setting the State
*
@ -396,7 +403,6 @@ namespace Cantera {
* @{
*/
//! Set the internally storred specific enthalpy (J/kg) and pressure (Pa) of the phase.
/*!
* @param h Specific enthalpy (J/kg)