Simulation of the influence of surface tension on granule morphology during spray drying using a simple capillary force model

•The influence of surface tension on the granule formation is investigated in detail.•Coupled CFD-DEM simulations are used including a simple capillary force law.•The simulations provide valuable insight into the mechanism of granule formation.•A clear correlation relates high surface tension with dense granules and vice versa.

Spray drying is an important process in powder technology as it transforms fine primary powder into processable granules. While various investigations of granule formation exist, the role of surface tension on the evolution of the granule morphology has not been investigated in much detail. This work closes this gap by using numerical simulations on granule level. In our simulation of suspensions of solid particles, we use the Discrete Element Method (DEM) in combination with a CFD solver. Due to the free liquid surface, a multiphase solver is needed including a force model for the particle-surface contact. As a result, our work gives insight into the granule formation and reveals a clear non-linear dependency relating high surface tension to dense granules.

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