A New Approach to the Evaluation of Transport Properties of Azeotropic and Quasi-Azeotropic Refrigerant Mixtures

Azeotropic and quasi-azeotropic mixtures of organic compounds could become the most effective candidates as replacement fluids in refrigeration devices and heat pumps. Following the development of effective prediction formulas for several families of pure organic compounds, in this paper the evaluation of transport properties of liquid mixtures is approached from a rather different point of view. Azeotropic and near-azeotropic mixtures are treated as pure compounds rather than as a combination of several pure substances. This is now possible, having developed a single, specialized formula for both the liquid thermal conductivity and the dynamic viscosity. The prediction method requires the knowledge of only a few equilibrium properties of the mixture to be analyzed and thus is a simple and powerful tool for the evaluation of alternative refrigerants. Each formula has been tested against experimental data and shows deviations below those required for engineering purposes. Important results have also been achieved on applying the same equations to quasi-azeotropic mixtures with deviations comparable to those for azeotropic mixtures.