Emulsions have a wide scope of applications. They can be found in the cosmetic, chemical, pharmaceutical, and food industry. Emulsion properties, such as stability, rheological behavior, and color depend on the droplet size and droplet size distribution (DSD) of the emulsion. High-pressure homogenization (HPH) is mostly used to produce emulsions with droplets smaller than one micrometer. During this process, an emulsion premix with larger droplets is pumped with a pressure of several hundred bar through a disruption unit. In this unit, the characteristic dimension through which the product flows, is significantly reduced. This results in a drastic increase in flow velocity. Thereby, droplets are exposed stresses resulting from laminar, turbulent and cavitating flow patterns, which cause droplet breakup. Nonetheless, the influence of geometrical or process parameters on resulting droplet sizes is still focus of ongoing research. Therefore, the design of a HPH process, which should result in a specific droplet size, is still mostly based on process functions and empirical knowledge.
This investigation focuses on the influence of the geometry of the disruption unit, and the process parameters on the local flow pattern and resulting stresses. ... mehr