Toward the modelling of surface tension of refrigerant mixture based on linear gradient theory

Abstract

Surface tension is one of the most important thermodynamic properties of the working fluids for the design of heat pumps, refrigerators and air conditioners. The Linear Gradient Theory have been widely used for the prediction of surface tension. Based on this theory and combining with the Peng-Robinson Equation of State, a novel model for surface tension calculation is proposed in this work. In this model, new correlation of pure substance influence parameter (PSIP) with temperature and correlation of binary interaction parameters for influence parameter (BIPc) with temperature and with composition, alongside with the adjustment method for these two parameters are proposed in order to optimize the model. The PSIPs of several common refrigerants and the BIPc of several binary mixtures are adjusted, while the new predictions with these adjusted parameters are done. Results with the adjusted parameters show a great consistency with the experimental data and a great improvement compare to the result obtained with the unadjusted parameters. The adjusted parameters can also be used to predict other mixtures with the same components but with different compositions.