Analysis of specific correlations and general models for the surface tension of six liquid oxides

Abstract

In this work, we analyze the validity and accuracy of two kinds of models that allow the correlation or prediction of the surface tension of fluids as a function of the temperature. In particular, the models are applied to six liquid oxides: carbon dioxide, carbon monoxide, nitric oxide, nitrous oxide, sulfur dioxide and sulfur trioxide. We include here two specific correlation models that contain adjustable coefficients for every fluid, and eleven predictive general models that employ fixed coefficients, valid for all the fluids. All of the models require the critical temperature as input, but the general models also need some other properties of the fluids, like the critical pressure or volume, or the acentric factor. The analysis is made through a comparison with the available data in the DIPPR and DETHERM databases, Wohlfarth and Wohlfarth's book, and some other sources. The obtained results show that the specific models provide mean absolute percentage deviations (MAPD) below 2.4% except for the case of carbon dioxide. There is no general model that can offer low MAPD values for all the fluids considered here. Nevertheless, except for the cases of carbon dioxide and nitric oxide, for each fluid there is at least one general model that provides an MAPD below 3%.