Description of the vapor-liquid equilibrium in binary refrigerant/lubricating oil systems by means of an extended Flory-Huggins model

In the present work, the extended Flory-Huggins equation is applied to describe the vapor-liquid equilibrium in binary mixtures usually used in refrigerating cycle machines and constituted by a fluorinated refrigerant (CFC) and a lubricating oil. With the purpose of testing the model, some isothermal measurements of equilibrium pressure have been carried out for mixtures with different CFC compositions in oil related to the refrigerants R134a, R143a and R236fa mixed with a commercial lubricating oil (Icematic SW32). Furthermore, the model has been applied to experimental data retrieved from the Literature, and the adjustable correlation parameters have been determined both for these, and for experimental isotherms. (C) 1999 Elsevier Science S.A. All rights reserved.