Viscosities of Liquid Refrigerants from a Rough Hard-Sphere Theory-Based Semi-Empirical Model

In this study, the application of a semi-empirical model for the prediction of dynamic viscosities of liquid refrigerants has been explored for both saturated and compressed states. The model used rough hard-sphere (RHS) theory in the model development; a smooth hard-sphere expression and a coupling parameter of translational–rotational motions were employed. Also, the model used the three inputs, the critical temperature, critical density, as well as the liquid densities, for which the values were taken from Carnahan-Starling-vdW-β equation of state (EoS). Most of the refrigerants investigated herein are those based on methane, ethane, and propane. The ability of the RHS-based model been checked by the calculation of dynamic viscosities of 26 liquid refrigerants at compressed states in the 200 K to 420 K range and pressures up to 50 MPa. The average absolute deviation of 4.47 % (for 1539 data points) and 5.22 % (for 121 data points), respectively, were obtained for the cases of compressed and saturated liquid refrigerants studied. The degree of accuracy of the present semi-empirical model has also been compared with the literature RHS-based models as well as other approach based on the viscosity EoS.