Species Reference-State Thermodynamic Properties

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. More...

Collaboration diagram for Species Reference-State Thermodynamic Properties:

Detailed Description

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.

The class SpeciesThermoInterpType is an abstract base class for calculation of thermodynamic functions for a single species in its reference state. The following classes inherit from SpeciesThermoInterpType.

• NasaPoly1 in file NasaPoly1.h
  • This is a one zone model, consisting of a 7 coefficient NASA Polynomial format.

• NasaPoly2 in file NasaPoly2.h
  • This is a two zone model, with each zone consisting of a 7 coefficient NASA Polynomial format.

• ShomatePoly in file ShomatePoly.h
  • This is a one zone model, consisting of a 7 coefficient Shomate Polynomial format.

• ShomatePoly2 in file ShomatePoly.h
  • This is a two zone model, with each zone consisting of a 7 coefficient Shomate Polynomial format.

• ConstCpPoly in file ConstCpPoly.h
  • This is a one-zone constant heat capacity model.

• Mu0Poly in file Mu0Poly.h
  • This is a multi-zone model. The chemical potential is given at a set number of temperatures. Between each temperature the heat capacity is treated as a constant.

• Nasa9Poly1 in file Nasa9Poly1.h
  • This is a one zone model, consisting of the 9 coefficient NASA Polynomial format.

• Nasa9PolyMultiTempRegion in file Nasa9PolyMultiTempRegion.h
  • This is a multiple zone model, consisting of the 9 coefficient NASA Polynomial format in each zone.

The most important member function for the SpeciesThermoInterpType class is the member function SpeciesThermoInterpType::updatePropertiesTemp(). The function calculates the values of Cp, H, and S for the specific species pertaining to this class.

A key concept for reference states is that there is a maximum and a minimum temperature beyond which the thermodynamic formulation isn't valid. Calls for temperatures outside this range will cause the object to throw a CanteraError.

Classes
class	ConstCpPoly
	A constant-heat capacity species thermodynamic property manager class. More...
class	Mu0Poly
	The Mu0Poly class implements an interpolation of the Gibbs free energy based on a piecewise constant heat capacity approximation. More...
class	MultiSpeciesThermo
	A species thermodynamic property manager for a phase. More...
class	Nasa9Poly1
	The NASA 9 polynomial parameterization for one temperature range. More...
class	Nasa9PolyMultiTempRegion
	The NASA 9 polynomial parameterization for a single species encompassing multiple temperature regions. More...
class	NasaPoly1
	The NASA polynomial parameterization for one temperature range. More...
class	NasaPoly2
	The NASA polynomial parameterization for two temperature ranges. More...
class	ShomatePoly
	The Shomate polynomial parameterization for one temperature range for one species. More...
class	ShomatePoly2
	The Shomate polynomial parameterization for two temperature ranges for one species. More...
class	SpeciesThermoInterpType
	Abstract Base class for the thermodynamic manager for an individual species' reference state. More...