Powder production by spray drying is achieved through the dehydration of droplets. The physical properties of the dried powder often influence its application. The drying kinetics of a single droplet of dextrin solution into the solid phase were monitored during the drying process. An acoustic levitator was used to suspend the droplet in the acoustic field. Such experiments are essential for achieving a fundamental understanding of the drying process. Droplets with different initial solid content (dextrin aqueous solution of 10% and 30%) were investigated at different gas drying temperatures. The drying curves were compared to the Reaction Engineering Approach (REA) model. A good agreement between the model prediction and the experimental results was demonstrated, with an absolute relative error of about 2% between the initial droplet mass and the droplet mass that the REA model predicted. The final particle diameter was estimated theoretically and compared to the experimental data. Single droplet simulations have enormous potential for drying step characterization of expensive compounds and highly potent drugs, due to the low amounts that the experiments require.
Keywords: Acoustic levitation; Drying kinetics modelling; Particle formation; Single droplet drying.
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