Aspen Physical Property System - Physical Property Models

Parameter Name †
/Element
CPIXPn/1 T n,l ig
CPIXPn/2 T n,h ig
CPIXPn/3 a n,i ig
CPIXPn/4 b n,i ig
CPIXPn/5 c n,i ig
CPIXPn/6 d n,i ig
CPIXPn/7 e n,i ig
CPIXPn/8 f n,i ig
CPIXPn/9 g n,i ig
CPIXPn/10 h n,i ig
2 Thermodynamic Property Models 231
Symbol Default MDS Lower
Limit
Upper
Limit
Units
— x — — TEMPERATURE
— x — — TEMPERATURE
— x — — ††
0 x — — ††
0 x — — ††
0 x — — ††
0 x — — ††
0 x — — ††
0 x — — ††
0 x — — ††
† n is 1 through 3. CPIXP1 vector stores ideal gas parameters for the first
temperature range. CPIXP2 vector stores ideal gas parameters for the second
temperature range, and so on.
†† TEMPERATURE, ENTHALPY, ENTROPY
Electrolyte NRTL Enthalpy Model
(HMXENRTL)
The equation for the electrolyte NRTL enthalpy model (HMXENRTL) is:
The molar enthalpy Hm * and the molar excess enthalpy Hm *E are defined with
the asymmetrical reference state: the pure solvent water and infinite dilution
of molecular solutes and ions. (here * refers to the asymmetrical reference
state.)
Hw* is the pure water molar enthalpy, calculated from the Ideal Gas model
and the ASME Steam Table equation-of-state. (here * refers to pure
component.)
Hs *,l is the enthalpy contribution from a non-water solvent. It is calculated as
usual for components in activity coefficient models:
Hs *,l (T) = Hs *,ig + DHVs(T,p) - �Hs,vap(T).
The term DHVs(T,p) = Hs *,v - Hs *,ig is the vapor enthalpy departure
contribution to liquid enthalpy; option code 5 determines how this is
calculated.
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The aqueous infinite dilution thermodynamic enthalpy Hk is calculated from
the infinite dilution aqueous phase heat capacity as follows: