Abstract Summary (Max 250 words)
As for liquid-liquid two-phase flow with mass transfer in macroscopic extraction equipment, droplet size distribution (DSD) is the key factor for transfer efficiency. Droplet behaviors, affecting the DSD, are correlated with interfacial tension which varies with the mass transfer process. To understand the evolution of the DSD under mass transfer, the droplet breakage kernels and dynamic interfacial tension (DIFT) were investigated. First, to obtain and use reliable breakage experimental data, the breakage kernel measurement methods in literature were summarized and reexamined. It was found the measurement definitions of breakage frequency in the most studies are not correct. Based on the correct combination between breakage fraction and total spent time, the suitable measurement standards for single droplet and droplet swarm experiments were established. Second, through analyzing droplet deformation and breakage process, the droplet collides with multiple eddies during its breakage time. The interaction between eddies and the droplet causes the droplet to oscillate, and the second-order oscillation breakage mechanism was determined. Reexamining three classic breakage constraints and introducing the concept of breakage similarity, the corresponding breakage model was constructed with experimental data, and the model exhibits satisfying prediction for droplet breakage in macroscopic extraction equipment with turbulent flow. Third, based on the relationship between breakage frequency and interfacial tension, a DIFT measurement method in a stirred tank was established by conducting droplet swarm experiment with a high-speed camera. The effects of impeller rotating speed, solute concentration and residence time on the DIFT were investigated. Besides, the DIFT is mainly determined by interfacial solute concentration and the method predicting DIFT was constructed with mass transfer results obtained by analyzing single droplet dispersion process. Finally, some studies concerning computational fluid dynamics - population balance model (CFD-PBM) were conducted with the correlations of breakage kernels and DIFT.
