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Keywords:

  • renormalized perturbation theory;
  • polarizability;
  • induced dipole;
  • mixtures;
  • SAFT;
  • equation of state

Abstract

The renormalized perturbation theory for polarizable polar fluids of Wertheim is applied in combination with a dipole contribution for non-spherical molecules to account for the non-additive induction interactions due to the polarization of molecules. A comparison to simulation data of pure polarizable dipolar fluids and mixtures reveals a good to excellent agreement between the renormalized perturbation theory and the simulations. The model framework is applied with the Perturbed-Chain SAFT equation of state to model phase equilibria of mixtures containing strongly polar components. The considered values of dipole moments and of average molecular polarizabilities stem from independent sources, and there is thus no additional adjustable parameter introduced along with the polar contributions to the equation of state. It is confirmed that accounting for dipolar interactions not only reduces the value of the binary interaction parameter, but in many cases significantly improves the description of pure-component and mixture phase equilibria. Accounting for molecular polarizability and the dipole induction effects only leads to slightly improved results compared to the case where a permanent dipole moment is considered in the calculations. © 2006 American Institute of Chemical Engineers AIChE J, 2006