Phase equilibrium and interfacial properties of water+methane mixtures

• Published in: Fluid phase equilibria 2016-01, Vol.407, p.143-151
• Main Authors: Niño-Amézquita, Oscar Gabriel, Enders, Sabine
• Format: Article
• Language: English
• Subjects: Computational fluid dynamics; Density gradients; Fluid flow; Fluids; Interfacial properties; Mathematical models; Methane; New combining rule; PC-SAFT modelling; Phase behavior; Solubility
• ISSN: 0378-3812; 1879-0224
• DOI: 10.1016/j.fluid.2015.05.005

•A new combining rule for the dispersion energy in the PC-SAFT-EOS is suggested.•The new combining rule allows the modeling of the solubility of methane in water as well as the solubility of water in methane in very good agreement with experimental data.•Using this combining rule in combination in the density gradient framework leads to a fair modeling of the surface tension in a wide pressure and temperature range; however, one temperature-independent mixing parameter is required.•The predicted interfacial profiles and interfacial tensions are in good agreement with other theoretical approaches and with molecular simulation results. This work aims to use the density gradient theory (DGT) for one alkane–water mixture, namely the methane+water system, combined with the perturbed chain statistical associating fluid theory (PC-SAFT) in order to model phase behavior and interfacial properties, simultaneously. A new combining rule taking into account the temperature as well the composition dependency for the dispersion energy parameter is suggested. Applying this new combining rule leads to very good agreement between the modeled and the experimental solubility of water in methane as well as the solubility of methane in water. The solubility minimum of methane in water as function of temperature could be captured. The calculation of the surface tension was possible also in accordance to the experimental data, if a binary, temperature-independent influence parameter is used. Other calculated interfacial properties, which can not be measured, are in agreement with molecular simulation data and with theoretical results based on the density gradient theory in combination with the SAFT-VR-Mie approach.