Aspen Physical Property System - Physical Property Models

Ti con,ig
240 2 Thermodynamic Property Models
= The temperature at which one crosses from vapor
state to liquid state. This is a user defined
temperature that defaults to the system temperature
T. Ti con,ig may be selected such that heat of
vaporization of component i at the temperature is
most accurate.
The ideal gas enthalpy is calculated as follows:
The vapor enthalpy is calculated as follows:
The liquid heat capacity and the ideal gas heat capacity can be calculated
from the General Pure Component Liquid Heat Capacity and General Pure
Component Ideal Gas Heat Capacity, or other available models. The heat of
vaporization can be calculated from the General Pure Component Heat of
Vaporization, or other available models. The enthalpy departure is obtained
from an equation of state that is being used in the property method. For
WILS-LR and WILS-GLR, the ideal gas equation of state is used.
Parameter Symbol Default MDS Lower
Name/Element
Limit
Upper
Limit
RSTATE — 1 † — — — —
TREFHI T i ref,ig
DHFORM H i ref,ig
TCONHI T i con,ig
Units
†† — — — TEMPERATURE
— — — — MOLE ENTHALPY
T — — — TEMPERATURE
† Enthalpy reference state RSTATE for a component. Value of 1 denotes ideal
gas.
††For components with TB � 298.15 K, RSTATE defaults to 1 (ideal gas).
TREFHI defaults to 298.15 K. For components with TB > 298.15 K, RSTATE
defaults to 2 (liquid) and TREFHI does not apply to these components. See
the Saturated Liquid as Reference State section for more details.
Helgeson Equations of State
The Helgeson equations of state for standard volume , heat capacity ,
entropy , enthalpy of formation , and Gibbs energy of formation
at infinite dilution in aqueous phase are: