On the evaluation of the interfacial turbulence (the Marangoni effect) in gas (vapour)—liquid mass transfer: Part I. A method for estimating the interfacial turbulence effect

Abstract

Two widespread approaches for evaluation of the influence, upon gas (vapour)—liquid mass transfer in the case of ‘positive mixtures’ (dσ/d x < 0), of the interfacial turbulence caused by the surface tension gradients (Marangoni effect) have been surveyed and analysed critically. It is shown that the assumption of direct proportionality of mass transfer enhancement and Marangoni number has not been well justified. Evidence is given which supports the concept of defining the enhancement factor by the ratio R = Ma/Ma c) n . Some problems concerning the enhancement dynamics of mass transfer, the initiation threshold of the Marangoni instabilities, as well as the limits of saturation have been discussed thoroughly. By correlating a large amount of experimental data from the literature, equations have been derived concerning the critical Marangoni number Ma c and the exponent n. These equations are proposed for use when accounting for the Marangoni effect in gas (vapour)—liquid systems regardless of contactor type and solutions employed, the enhancement effect being obtained in relation to local mass transfer efficiency.