Empirical correlations for second virial coefficients of nonpolar and polar fluids covering a wide temperature range

Abstract

Being of great value in calculating the effect of the vapor-phase nonideality, second virial coefficients can be accurately described by the corresponding-state principle. Based on the corresponding-state principle, the new generalized second-virial-coefficient correlations of simple, nonpolar and non-associated polar fluids were proposed in this work. Four mathematical criterions for second-virial-coefficient models were summarized on the basis of the temperature-dependent characteristics of molecular interactions and macroscopic properties. Covering a wide temperature range which had never been reached before, the new-form correlations met the four mathematical criterions strictly. Ab initio values, together with the carefully selected high-quality experimental data, were used to define the “perfect” simple fluid and fitted satisfactory with the present simple spherical and nonpolar terms. More experimental data of second virial coefficients for non-associated polar fluids were collected and the refitted polar term yielded more reliable and physically-reasonable results.