VLE/VLLE/LLE Predictions for Hydrogen Fluoride Mixtures Using an Improved Thermodynamic Equation of State

Abstract

Recently a model has been introduced describing the heat effects of hydrogen fluoride (HF) more accurately than other models available. In this work, we extend this model to predict the coexistence properties of some binary HF mixtures. Twelve HF mixtures are explored initially (R12, R22, R32, R113a, R123, R124, R134a, R142b, R152a, n-propane, HCl, and Cl2) because these are the systems where experimental data are available. Good agreement with experiment, especially in the correlation of miscibility gaps, is realized through the use of two mixing rules, namely, van der Waals (VDW) and Wong−Sandler. We also correlate the binary interaction parameter from the VDW mixing rule using the dipole moment to predict the properties of the HF−R141b system. We also use this model to correlate and predict the properties of an aqueous HF system, including a prediction for a double azeotrope of this system at very dilute concentrations of HF.