Analysis of the Combinations of Property Data That
Are Suitable for a Safe Estimation of Consistent Twu α‑Function
Parameters: Updated Parameter Values for the Translated-Consistent tc-PR and tc-RK Cubic Equations of State
posted on 2018-09-27, 00:29authored byAndrés Pina-Martinez, Yohann Le Guennec, Romain Privat, Jean-Noël Jaubert, Paul M. Mathias
The
suitability of different combinations of property data among
vapor-pressure (Psat), enthalpy of vaporization
(ΔvapH) and saturated-liquid heat-capacity
(cP,liqsat) data for fitting consistent Twu α-function
parameters is evaluated. A given combination is declared to be suitable
if the obtained fitted parameters produce acceptable predictions for
the three considered properties for the 783 molecules included in
the reference database. Calculations are carried
out using the translated-consistent versions of the
Peng–Robinson (tc-PR) and Redlich–Kwong
(tc-RK) cubic equations of state (CEoS). It is demonstrated
that reliable parameters are obtained on the condition that they are,
at least, fitted to vapor-pressure data. It is strongly advised to
not exclusively fit α-function parameters to enthalpy of vaporization
and/or saturated-liquid heat capacity data. Finally, Twu α-function
parameters (L, M, N) suitable for the tc-PR and tc-RK CEoS are determined for the 1721 molecules, for which
at least accurate vapor-pressure data are available in the DIPPR database.
The volume-translation parameter c has also been
determined but for only 1489 pure fluids. In addition, the generalized
versions of the tc-PR and tc-RK
CEoS (“generalized” means that the input parameters
of these models are the experimental critical temperature, critical
pressure, and acentric factor) are updated.