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Superancillary Equations for Nonpolar Pure Fluids Modeled with the PC-SAFT Equation of State
Published
Author(s)
Ian Bell, Ulrich Deiters
Abstract
Superancillary equations are presented for the PC-SAFT equation of state of Gross and Sadowski for nonpolar pure fluids. The equations cover the range of a number of segments from 1 to 64. These equations, formed as nested sets of Chebyshev expansions, represent the densities for vapor–liquid equilibria better than can be achieved by iterative calculations in double precision arithmetic. Furthermore, the expressions are more than 16 times faster to evaluate than the iterative calculations from the fastest thermodynamic property library. By their construction, the superancillary equations are guaranteed to be reliable over the entire temperature range. For user-friendliness, the functions have been packaged into a Python package available on PYPI.
Bell, I.
and Deiters, U.
(2023),
Superancillary Equations for Nonpolar Pure Fluids Modeled with the PC-SAFT Equation of State, Industrial and Engineering Chemistry Research, [online], https://doi.org/10.1021/acs.iecr.2c02916, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935213
(Accessed October 9, 2025)