Vapor-liquid equilibrium simulations of nitrogen and n-alkane binary mixtures

Molecular dynamics simulations have been carried out to study nitrogen-n-alkane binary mixtures in the liquid-vapor phase equilibrium. The coexisting densities, composition, vapor pressure, and surface tension of mixtures are calculated in a wide range of pressures at constant temperature. The n-alkane molecules varied from n-pentane to n-decane. The coexistence diagrams were obtained using a recently developed potential model for n-alkane molecules, NERD. Results from this work show that these potential models reproduce available experimental data at low and moderate pressures for the composition-pressure diagram. The models over-predicted the vapor pressure compared with experimental data. At the same temperature and pressure, the surface tension increases with n-alkane chain length. At 310.93 K and 200 bars, the surface tension increased about 90% by changing n-hexane for n-decane in the binary mixture. (C) 2002 Elsevier Science B.V. All rights reserved.