Characteristics of a motionless mixer for dispersion of immiscible fluids-II. Phase inversion of liquid-liquid systems

Phase inversion in liquid-liquid systems flowing in a motionless mixer was studied using the modified electroresistivity method published in Part I of this series (Sembira A., Merchuk J.C. and Wolf D., Chem. Engng Sci. 1986 41 445). The pairs of liquids used were: (a) water-kerosene, (b) water-CCl₄ and (c) water-(kerosene + CCl₄). Sulzer SMV-4 mixing elements made of stainless steel (SS316) and identical elements coated with a film of Teflon were used. On the basis of the experimental results, it can be concluded that (a) the metastable or ambivalent zone is very narrow; (b) at low flow rates the nature of the surface of the mixing elements has a strong influence on the phase inversion phenomenon; (c) at high flow rates the nature of the surfaces has a weak influence and the inversion occurs when the volume fraction of the dispersed phase is close to 0.5. A predictive model based on free energy consideration is derived. The model describes the results reported satisfactorily.