Systematic study of vapour–liquid equilibria in binary mixtures of fluids with different polarity from molecular simulations

Abstract

For engineering applications, one of the most important characteristics of fluid mixtures is the vapour–liquid equilibrium (VLE). Knowledge of the VLE of mixtures containing simple model components like Lennard-Jones (LJ) and Stockmayer (ST) fluids can offer insight into how different modes of molecular interaction shape the phase behaviour of mixtures. However, studies investigating such mixtures are still scarce in the literature, especially for mixtures with an LJ fluid as the high boiling substance. In this work, the VLE of mixtures consisting of LJ and ST fluids are studied with molecular simulation using the Grand Equilibrium method. The energy parameter and length parameter of the LJ fluids and the dipole moments of the ST fluids are varied systematically to generate different types of mixtures. These mixtures are investigated within a broad temperature range. VLE envelopes and molarities are reported as well as additional data on the bubble and dew line including enthalpies, chemical potentials, and activity coefficients. These data fill a gap in the literature by furthering the understanding of how polarity affects phase behaviour in mixtures and are therefore of critical importance, e.g. for the development of theoretical approaches for the description and prediction of phase behaviour for polar mixtures.