Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

The solid-liquid-gas equilibrium data of four fatty acids (lauric acid, myristic acid, palmitic acid and stearic acid) and ibuprofen in high-pressure nitrogen were measured by using the first melting point method. Results showed that the melting temperature of the solutes increases slightly with the increase of the nitrogen pressure in the investigated pressure range (0.1-13 MPa). A correlation model consisted of the Peng-Robinson equation of state (PR EoS), the van der Waals one fluid (vdW-1) mixing rule and the NRTL equation was employed to calculate the solid liquid gas lines of these systems and the naphthalene + N2 and benzene + N2 systems. Furthermore, two models constructed of PR EoS + vdw-1 + UNIFAC and PR EoS +MHV1 (or LCVM or a modified LCVM) + UNIFAC were, respectively, applied to the prediction of the solid liquid gas lines of the systems. A simplified model was also examined by assuming zero solubility of N2 in melted solutes. Results indicated that the correlation model presented fairly good calculations of the solid liquid gas equilibrium data, the prediction models gave satisfactory results, and the simplified model could serve as an estimation method for trend prediction.