Modelling and simulation of extensional-flow units in emulsion formation

In this contribution we studied the emulsification process carried out in an extensional-flow unit. By means of rigorous population and momentum balances we captured the phenomenological description of the first principles occurring in such unit. The strong feature of our model approach resides in the fully mechanistic description of the governing phenomena. Namely, a population balance equation was formulated and solved to account for the disappearance and appearance of droplets at each size class. Moreover, coalescence mechanism was included to account for the instability of newly created droplets. Additionally, our model estimated the prevailing break-up mechanism at each size class as a function of droplet diameter, the acting forces on the droplet and the exposure time in the high energy zone. We validated the accuracy of the results obtained from our equation-based model with experimental data obtained at pilot-plant scale. The results obtained by simulation showed that at a given set of operational conditions and pre-emulsion properties the product obtained was within the desired and narrow specifications space. As a concluding remark of this study we suggest further exploring the design and development of extensional-flow units for the creation of structured emulsions.