Carbon Dioxide + Fluoromethane and Nitrous Oxide + Fluoromethane: Solid−Liquid Equilibria Measurements

A recently built experimental setup was employed for the estimation of the solid-liquid equilibria (SLE) of alternative refrigerant systems. The behavior of two binaries, that is, carbon dioxide + fluoromethane (CO2 + R41) and nitrous oxide + fluoromethane (N2O + R41), was measured down to temperatures of 126.5 K. To confirm the reliability of the apparatus, the triple points of the pure fluids constituent of the binary systems were measured. All triple-point data measured revealed a generally good consistency with the literature. The results obtained for the mixtures were corrected by the Rossini method and interpreted by means of the Schröder equation. © 2010 American Chemical Society

An algorithm for the regression of the UNIQUAC interaction parameters in liquid-liquid equilibrium for single- and multi-temperature experimental data

This paper describes an algorithm for the computation of the UNIQUAC interaction parameters from liquid-liquid experimental data. The algorithm comprises two separate levels. The inner level is devoted to the calculation of the interaction parameters, minimizing an objective function which is function of the activities. The outer level uses the parameters by the inner level and aims to minimize the error between experimental and calculated molar fractions through an adjustment of the experimental molar fractions, provided that the condition of common tangent to the change of the Gibbs free energy of mixing is matched. The algorithm is applied to seven binary systems for the evaluation of single temperature parameters and to the tetrahydrofuran/water system for the evaluation of the temperature dependent parameters. In both cases, the calculated parameters provide results with lower error than the previously published parameters. In all cases thermodynamically consistent and precise results are obtained in terms of common tangent of the Gibbs free energy of mixing and molar faction errors

Solid–liquid equilibria measurements of the carbon dioxide+2,3,3,3-tetrafluoroprop-1-ene and carbon dioxide+trans-1,3,3,3-tetrafluoropropene mixtures

A built experimental set-up was employed for the estimation of the solid–liquid equilibria of alternative refrigerants systems. The behavior of two binaries, i.e. carbon dioxide + 2,3,3,3-tetrafluoroprop-1- ene (CO2 + R1234yf) and carbon dioxide + 1,3,3,3-tetrafluoropropene (CO2 + R1234ze(E)), was measured down to temperatures of 122.6 K. The triple points of the pure fluids constituent the binary systems were measured, together with the triple points of the two mixtures with varying their composition. The results obtained for the mixtures were interpreted by means of the Schröder equation