Coalescence efficiency in binary systems

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The project has its focus on fundamental research regarding binary droplet-droplet coalescence. Both groups combine their experience of droplet and droplet swarm behavior in order to improve and quantify the basic phenomena related to droplet coalescence. The results from the first project confirmed, that the mutual cooperation will bring synergies in handling the complex phenomenon of coalescence of droplets. After establishing standardized procedures (EXP2 to 4) and test rigs (EXP 1) a successful data acquisition started. The obtained results cannot be simulation with existing coalescence kernels, and existing models will be improved in that respect. Special attention will be drawn to hydrodynamic (contact time, relative velocity, etc.) and chemical (pH-value, salts, ionic strength, etc.) conditions, in order to span a wide data field to gain a predictive model. In that respect an additional test system heptane/water is considered, with almost same viscosity as toluene/water but higher interfacial tension promoting coalescence. CFD studies should additionally help to visualize phenomena in experimentally difficult to explore domains, especially with film rupture and outflow at initial coalescence. The validation of the new kernels will be done by the two groups in either stirred vessels or extraction columns.