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Aspen Physical Property System - Physical Property Models

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Parameter<br />

Name<br />

Applicable<br />

Components<br />

CPIG Molecular Solutes C p,i *,ig<br />

Water, Solvents C p,w *,ig<br />

2 Thermodynamic <strong>Property</strong> <strong>Models</strong> 235<br />

Symbol Default Units<br />

— †††<br />

— †††<br />

† IONTYP and SO25C are not needed if CPAQ0 is given for ions.<br />

†† DGFORM is not needed if DHAQFM and CPAQ0 are given for molecular<br />

solutes.<br />

††† The unit keywords for CPIG are TEMPERATURE and HEAT-CAPACITY. If<br />

CPIG/10 or CPIG/11 is non-zero, then absolute temperature units are<br />

assumed for CPIG/9 through CPIG/11. Otherwise, user input temperature<br />

units are used for all elements of CPIG. User input temperature units are<br />

always used for other elements of CPIG.<br />

Option Codes for Electrolyte NRTL Gibbs Free Energy<br />

Model (GMXENRTL)<br />

The electrolyte NRTL Gibbs free energy model (GMXENRTL) has six option<br />

codes and the option codes can affect the performance of this model.<br />

Option code 1. Use this option code to specify the default values of pair<br />

parameters for water/solute and solvent/solute; the solute represents a<br />

cation/anion pair. The value (1) sets the default values to zero and the value<br />

(3) sets the default values for water/solute to (8,-4) and for solvent/solute to<br />

(10,-2). The value (3) is the default choice of the option code.<br />

Option code 2. Use this option code to specify the vapor phase equation-ofstate<br />

(EOS) model used for the liquid Gibbs free energy calculation. The value<br />

(0) sets the ideal gas EOS model and the value (1) sets the HF EOS model.<br />

The value (0) is the default.<br />

Option code 3. Always leave this option code set to the value (1) to use the<br />

solvent/solvent binary parameters obtained from NRTL parameters.<br />

Option code 4. Not used.<br />

Option code 5. Use this option code to specify how the pure vapor phase<br />

fugacity coefficient (PHIV) is calculated. The value (0) sets PHIV = 1 (ideal<br />

gas law), the value (1) specifies using Redlich-Kwong equation of state, and<br />

the value (3) specifies using Hayden-O’Connell equation of state. The value<br />

(0) is the default.<br />

Option code 6. Use this option code to specify the method for handling<br />

Henry components and multiple solvents. The value (0) sets the pure liquid<br />

Gibbs free energy to that calculated by aqueous infinite dilution heat capacity<br />

(only water as solvent) and the value (1) sets the pure liquid Gibbs free<br />

energy for Henry components using Henry’s law. Use value (1) when there<br />

are multiple solvents. The value (0) is the default.<br />

Liquid Enthalpy from Liquid Heat Capacity<br />

Correlation<br />

Liquid enthalpy is directly calculated by integration of liquid heat capacity:

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