Vortex-Based cavitation devices for continuous emulsification: Influence of the device design, scale-up, and scale-out

Continuous emulsification is a desirable alternative to batch processing, especially in sectors such as food and beverage, cosmetics, and pharmaceuticals, where large volumes of consistent emulsions are required. Vortex-based hydrodynamic cavitation (VD) devices have emerged as efficient and scalable options using cavitation-induced local energy dissipation to promote droplet breakup. However, practical guidance for device design and pathways for scale-up and scale-out remains limited. This study investigates the influence of the outlet configuration, chamber geometry, number of inlets, and scale-up or scale-out on the performance of VD for continuous production of liquid−liquid emulsions. The results indicate that including a vortex stabilizer in the chamber and using a multiple-inlet device improved the cavitation activity. Geometrically similar scale-up (1−5 LPM) resulted in a slight increase in the Sauter mean diameter and lower energy efficiency, which confirmed the flow characteristics related to the distribution of turbulence dissipation rates becoming attenuated at larger scales. The scale-out options were investigated considering two and four 1 LPM nominal flow rate devices operated in parallel to increase the nominal flow rate to 5 LPM for the four devices. The results confirm that while scale-up and scale-out have limited impact on final droplet size distribution, they influence energy effectiveness. Multi-inlet designs were seen to enhance emulsification efficiency and reduce droplet size, especially when operating at low pressure drop values. Overall, this study provides practical guidelines for designing and deploying vortex-based HC devices for continuous emulsification applications.