High pressure phase equilibrum behaviour of naphthalene in supercritical co2 experimental results and calculation with the peng-robinson equation of state

International audiencePhase equilibrium calculations involving a pure solid component are presented. The fluid phases are modelled using the Peng-Robinson's equation of state (EoS) using two different mixing rules for the covolume of mixing: the classical linear mixing rule and the van der Waals or quadratic mixing rule with a binary interaction parameter. The pure solid chemical potential used in the model does not require the value of the sublimation pressure-it is based on the measurements made with a differential scanning calorimeter of the melting point of the solid. This model has been used for estimating the solubility of naphthalene in carbon dioxide (CO2). Experimental results have been obtained with an original apparatus, based on an open-circuit analytical method. These high accuracy measurements of the solubility of naphthalene in CO2 up to the supercritical region have been compared with the predicted values. The binary interaction parameters have been optimised using a parametric identification method. With these parameters a phase diagram of the binary mixture naphthalene-CO2 is calculated