Equations of State
Equations of state are applicable to wide ranges of temperature and pressure conditions. They can be used to calculate all of the related thermodynamic properties such as K-value, enthalpy, entropy and density. The reference state for both liquid and vapor is the ideal gas and deviations from ideal behavior are determined by calculation of the fugacity coefficients for both phases. For cubic equations in particular, critical and pseudocritical conditions can also be predicted quite accurately.
The following equations of state are available:
SRK-Panagiotopoulos-Reid (SRKP)
SRK-Modified Panagiotopoulos-Reid (SRKM)
PR-Modified Panagiotopoulos-Reid (PRM)
Benedict-Webb-Rubin-Starling (BWRS)
All thermodynamic properties are derived from each equation of state with these exceptions:
For SRK, SRKKD, SRKH, SRKP, SRKM, SRKS, PR, PRP, PRM, PPR78 and UNIWAALS the liquid density is determined with the API method.
Additional Information
Descriptions of the individual thermodynamic methods may be accessed from the Thermodynamic System - Modification Window by selecting the type of property, i.e., K-value, liquid enthalpy, etc., the method and pushing the Help button.
Refer Equations of State in PRO/II Reference Manual, Chapter 2, Volume 1 for more detailed information.
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