Properties of alternative refrigerants and heat transfer liquids — Modeling and experiments

The article provides a brief summary of two decades of both experimental and theoretical research on the thermophysical properties of refrigerants and heat transfer liquids carried out at the Thermodynamics department of IT CAS. The aim is to accurately describe properties of various fluids showing on one hand promising potential for technical applications or on the other scientifically interesting behavior. The selected systems cover various refrigerants and aqueous systems applicable as heat transfer liquids such as water with ethylene glycol, methanol, ethanol or sodium chloride. Current focus is mostly on hydrofluoroethers (HFEs) that find high application potential, e.g., in electronics cooling and cleaning or as possible admixtures in re-frigerant blends. The thermodynamic properties and phase equilibria of various refrigerants were successfully modeled with the state-of-the-art equations of state (EoSs) of SAFT-type (statistical associating fluid theory) supported by common cubic EoSs such as Peng-Robinson. The employment of density gradient theory enabled prediction of vapor-liquid phase interfaces and the surface tension of pure fluids and binary mixtures. The pressure-temperature-density relations are being investigated experimentally by using self-calibrated vibrating tube densimeters and single-sinker buyoancy method. The temperature dependence of surface tension is deter-mined with the Wilhelmy plate method, du Noüy ring and the in-house developed capillary rise technique. The viscosity is measured using rotating viscometers. Although the article summarizes twenty years of research, it presents new results that have not yet been published, e.g., for PC-SAFT EoS and its combination with the density gradient theory on halogenated refrigerants, or for the experimental data on the density and viscosity of ethylene glycol and the surface tension of HFE-7200.