Thermodynamic and transport properties of nitrogen and butane mixtures

A force field has been developed to describe the phase behaviour, interfaci al, and transport properties of nitrogen and hydrocarbon mixtures under con ditions relevant to those found in the high pressure extraction of oil from underground reservoirs. A Gibbs ensemble Monte Carlo method is used to par ametrize intermolecular potentials for the pure components by matching expe rimental and simulated liquid and vapour coexisting densities. Also the sur face tension, diffusion coefficient and shear viscosity of nitrogen and its mixtures with butane: have been determined. The latter properties were obt ained by canonical molecular dynamics simulations. The diffusion coefficien t and shear viscosity were calculated by a Green-Kubo method. Results for p ure nitrogen are given for temperatures ranging from 70 K to 110 K. For mix tures of nitrogen with butane, results are presented at 339.4 K and 380.2 K . Good agreement is found between the results of simulations and available experimental data.