A new equation of state, in which the group contribution method appears as an inherent result of the approximations used to generate the model, is studied to calculate phase equilibrium thermodynamic properties. The group contribution equation of state (GC-EOS) is based on the generalized van der Waals theory and combines the Staverman-Guggenheim combinatorial term with an attractive lattice gas expression. By using a data bank of pure substances and binary mixtures of linear hydrocarbons, four different schemes of fitting the parameters of alkane groups (CH3 and CH2) are presented. Consistent with the genesis of the proposed equation, we have found that the interaction energy and hard core volume parameters are not strongly temperature dependent functions. The results show that, with any parameter set obtained from different schemes, the GC-EOS describes vapor pressures of pure linear alkanes up to C12 with less than 4.5% deviation from experimental values. The GC-EOS is also able to describe bubble pressures of binary mixtures of linear alkanes with less than 5% deviation. Predicted vapor pressures of eight heavy hydrocarbons (from C14 to C28) and bubble pressures of highly asymmetric mixtures are in satisfactory agreement with experimental data.
|Number of pages||14|
|Journal||Brazilian Journal of Chemical Engineering|
|Publication status||Published - Sep 1996|
ASJC Scopus subject areas
- Chemical Engineering(all)