Empirical correlation of the surface tension versus the viscosity for saturated normal liquids

TL;DR

This study evaluates the effectiveness of Pelofsky's empirical correlation between surface tension and viscosity for 56 normal liquids across various temperatures, highlighting the substance-dependent nature of the correlation's parameters.

Contribution

It systematically compares the original and modified Pelofsky correlations for a wide range of non-ionic fluids, providing coefficients and temperature ranges for accurate surface tension predictions.

Findings

Original correlation works well for many fluids within certain temperature ranges.

Modified correlation with an exponent improves accuracy but is substance-dependent.

Both models achieve less than 1% average deviation within specific temperature limits.

Abstract

In 1966 Pelofsky proposed an empirical linear correlation between the natural logarithm of the surface tension and the reciprocal viscosity, which seems to work adequately for a wide range of fluids. In particular, it has been shown that it is useful in the case of n-alkanes and their binary and ternary mixtures. More recently however, it has been found not to work for several ionic liquids unless the reciprocal viscosity is raised to a power. The exponent of this power was fixed to be 0.3, at least for the studied ionic fluids. In the present work, the performance and accuracy of both the original Pelofsky correlation and the modified expression including the exponent are studied for 56 non-ionic fluids of different kinds over a broad range of temperatures. Also, the temperature range is delimited for which each expression reproduces the surface tension values with average absolute deviations below 1%. The needed coefficients are given for both the broad and the delimited temperature range for each expression. Unfortunately, the results show that the value of the exponent in the modified Pelofsky expression is substance-dependent for the normal fluids studied.