Density gradient theory study of surface tension of pure and mixture of refrigerant fluids with the help of perturbed-hard-chain equation of state

This work addresses the density gradient theory (DGT) modeling of surface tensions of pure and binary mixtures of Refrigerant fluids with the help of a perturbed-hard-chain equation of state using an attractive term of Yukawa tail. The DGT + PHC model employs both several molecular and an influence parameters (IP) as adjustable parameters. An analytical expression of the IP as a function of the temperature with 5 adjustable coefflcients is provided to obtain so low average deviations from the literature data. The average absolute deviations (AADs) of the present calculations from the NIST surface tension data as well as the experimental surface tensions taken from other literature sources were found to be 0.37% and 1.45%, respectively. Furthermore, the present DGT + PHC model has been extended to binary mixtures of refrigerants using some simple combining rules and two adjustable parameters, as well. In this respect, for 325 experimental data points examined, the AAD of the correlated surface tensions was equal to 1.38%. Finally, the degree of accuracy of DGT + PHC model has also been checked by comparing with two other DGT-based models cited in literature.