Influence of Atomization Geometry and Atomization Process Conditions on Oil Droplet Size in the Atomization Step During Spray-Drying of Emulsions

Spray-drying of emulsions is a widespread encapsulation technique for the production of a large number of powdered formulations, which is mainly used in the food, pharmaceutical and chemical industry. In this work, we focused on the influence of atomization process conditions and nozzle geometry on the oil droplet breakup. In detail, the impact of different atomization pressures as well as inlet port and outlet orifice dimensions on the oil droplet size after atomization using pressure-swirl nozzles were investigated. Atomization of a model oil-in-water food emulsion was performed with a spraying rig at 5 to 25 MPa. The results show a significant influence of the atomization pressure on oil droplet breakup during atomization of emulsions. The nozzle geometry exerts a minor but specific influence on oil droplet breakup and the results indicate changes of the flow characteristics inside the nozzle. However, these changes cannot be properly characterized by current mechanistic models.