Modeling the viscosity of hydrofluorocarbons, hydrofluoroolefins and their binary mixtures using residual entropy scaling and cubic-plus-association equation of state

Abstract Hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), and their binary mixtures are widely-used working fluids in moderate and low temperature energy systems. An accurate viscosity model is the cornerstone for the economic and conceptual optimization of the energy utilization systems. In this work, we apply residual entropy scaling and the cubic-plus-association (CPA) equation of state to HFCs, HFOs, and their binary mixtures. The reduced viscosity (real fluid viscosity divided by dilute gas viscosity) of 14 pure fluids are correlated to a univariate function of the residual entropy, which is calculated with the CPA equation of state, a model that was recently adapted for the thermodynamic properties of HFCs/HFOs. Then the viscosity of 10 binary mixtures are predicted by the model without introducing any further adjustable parameters. The present model reproduces the viscosity of the investigated pure fluids and mixtures accurately in both the gas and liquid phases and presents reliable predictions in temperature and pressure ranges in which the experimental data are scarce or unavailable.