Article ID Journal Published Year Pages File Type
202030 Fluid Phase Equilibria 2012 11 Pages PDF
Abstract

Combining Peng–Robinson (PR) equation of state (EOS) with Liu et al.’s association contribution derived from shield-sticky model (SSM), a new cubic-plus-association (CPA) EOS is proposed to describe the thermodynamic properties of pure associating fluids and their mixtures. The CPA-SSM EOS contains five molecular parameters (a0, c1, b, ω and δɛ/k) for the pure associating fluids, while for non-associating fluids it reduces to PR EOS with three molecular parameters (a0, c1, b). The molecular parameters are obtained by fitting the saturated pressures and/or liquid molar volumes at wide temperature ranges. The overall average absolute deviations (AADs) of 58 pure associating fluids and 20 non-associating fluids are 0.74% and 0.54% for saturated vapor pressure, 2.00% and 1.85% for liquid molar volumes respectively. The enthalpies of vaporization for 13 pure associating fluids are well predicted by using these molecular parameters. The molecular parameter b for homologous substances shows a good linear relationship with respect to their corresponding molecular weights. Using one temperature-independent binary adjustable parameter kij, satisfactory results of vapor–liquid equilibria (VLE) for both self- and cross-associating systems are obtained. The overall AADs of the equilibrium temperatures, pressures and vapor phase mole fractions are 1.46 K, 1.26 kPa and 0.0197 respectively for 25 self-associating systems, and 0.75 K, 0.50 kPa and 0.0155 respectively for 29 cross-associating systems. Other caloric properties such as the excess molar enthalpies of mixing are also successfully computed. The CPA-SSM EOS proposed has been proved to have comparable accuracy as other models but with much simpler form.

► The CPA-SSM EOS is proposed by combining PR EOS with Liu et al.’s association model. ► The model parameters are obtained for various kinds of associating fluids. ► Satisfactory results of VLE are obtained. ► Other caloric properties are successfully predicted. ► The CPA-SSM EOS has simpler form than other models but comparable accuracy.

Related Topics
Physical Sciences and Engineering Chemical Engineering Chemical Engineering (General)
Authors
, , , , , ,