Reference State
The reference temperature, pressure and phase can be specified for each package and for species within a package. The reference phase can be a real phase or an ideal gas. If a reference temperature, pressure, or phase is unspecified for a particular species, the package reference temperature, pressure, or phase is used for that species.
The reference values for enthalpy,
H
i,ref
, entropy,
S
i,ref
, and internal energy,
U
i,ref
, are calculated so that the pure species enthalpy, entropy, and internal energy are equal to zero at reference conditions.
The reference values for enthalpy, including formation terms, and entropy, including absolute terms, are calculated such that the corresponding property for pure species
i
has a value equal to the specified formation term at the species reference conditions.