Calculation of complex phase equilibria of DMF/alkane systems using the PCP-SAFT equation of state

Abstract

The Perturbed Chain Polar Statistical Association Fluid Theory (PCP-SAFT) equation of state is applied to calculate phase equilibria data for several DMF/alkane systems. DMF/alkane systems exhibit a peculiar phase behavior, due to overlapping liquid-liquid and vapor-liquid coexistence regions. Hetero- and homoazeotropes appear and disappear depending on temperature/pressure conditions and the chain length of the alkane. The vapor-liquid, liquid-liquid and vapor-liquid-liquid equilibria of DMF/alkanes systems including alkanes from C5 to C10 were studied in detail over wide temperature and pressure ranges. A single, linear expression for the binary interaction parameter kij as function of temperature and alkane chain length was used to model the experimental data. This expression was determined only by using experimental liquid-liquid equilibria (LLE) data of DMF/alkane systems. Using that, the PCP-SAFT equation of state provides very satisfying results for the description of the phase behavior in all considered systems. © 2013 Elsevier Ltd.