Drop coalescence in liquid‐liquid fluidized beds

A drop size segregation technique leads to a direct measurement of the interdrop coalescence frequencies of equisized droplet swarms in liquid‐liquid fluidized beds. Mass transfer between the phases and the use of a tracer dye are avoided. The study includes the effects of highly viscous continuous as well as dispersed phases. Binary liquid solutions of ethylene glycol and distilled water provided aqueous phases of increasing viscosity, and toluene was the second liquid phase. Twenty two liquid‐liquid systems including other dispersed liquids, namely, benzene, ethyl acetate, cyclohexane, and carbon tetrachloride, were studied by this technique. In the case of toluene continuous, the drops of water dispersed in toluene were large in size, and they coalesced at unusually high rates up to about 100 times faster than those of toluene dispersed in water. Similarly, anhydrous ethylene glycol dispersed in toluene showed somewhat high coalescence frequencies. All the data excluding these two anomalous systems were analyzed by a stepwise regression technique to yield the best fitting correlation in terms of the most significant dimensionless ratios. For the present, the proposed empirical correlation for the dimensionless parameter [ω D × 10 5 / V s ] containing the coalescence frequency (ω, time −1 ) as a function of the coalescence number (σ/μ c V s ) and the viscosity ratio (μ d /μ c ) is as follows:\documentclass{article}\pagestyle{empty}\begin{document}$$({{\omega D \times 10^5 } \mathord{\left/ {\vphantom {{\omega D \times 10^5 } {V_s }}} \right. \kern-\nulldelimiterspace} {V_s }}) = 0.020({\sigma \mathord{\left/ {\vphantom {\sigma {\mu c}}} \right. \kern-\nulldelimiterspace} {\mu c}}V_s)^{1.18} ({{\mu d} \mathord{\left/ {\vphantom {{\mu d} {\mu c}}} \right. \kern-\nulldelimiterspace} {\mu c}})^{0.450} $$\end{document} .