Prediction of viscosity of refrigerants and refrigerant mixtures

Abstract

We have developed a predictive corresponding states model for the viscosity of pure refrigerants and refrigerant mixtures. The model uses extended corresponding states with R134a (1,1,1,2-tetrafluoroethane) as the reference fluid. The model uses equilibrium shape factors and an equivalent substance reducing ratio (ESRR) for the viscosity which involves the molecular mass. The “mass” ESRR is found using viscosity data along the saturation boundary. We have fit these mass ESRR's to a general form involving reduced temperature and a structural factor. In addition, we have determined a set of universal coefficients for the mass ESRR that can be used to predict the viscosity of any halocarbon refrigerant given the critical parameters and the structural parameter. We give sample results comparing the model predictions with experimental data for pure fluids and a refrigerant mixture.