Phase Equilibrium Calculations for Asymmetric Binary Mixtures Using Group Contribution Method

Phase equilibrium for carbon dioxide + n-alkanes (methane, propane and n-pentane) asymmetric binary systems was calculated using Peng–Robinson (PR) and Nasrifar-Bolland (NB) equations of state coupled with van der Waals one-fluid mixing rules. Because of the PR EOS and NB EOS similarities, it is proposed by Farshchi Tabrizi and Nasrifar (2010) that the group contribution method developed by Jaubert et al. which known as PPR78 can serve the NB EOS reasonably if a and b of the PPR78 are replaced with those of the NB EOS, therfore the binary interaction parameter is calculated from the PPR78 for both equation of state in three asymmetric binary mixtures. In whole of the cases, the deviation between the experimental data and the calculated values with the proposed model was most accurate than those calculated deviations with kij=0. This superiority demonstrate the reliability of PPR78 model to used with NB EOS in addition to PR EOS.

Keywords:

Equation of state , Vapor-liquid equilibrium , Binary interaction parameters