Atomization of Liquids Relevant to Pharmaceutical Tablet Coating. Experiments and Droplet Size Modelling

This paper describes a collaborative theoretical and experimental research effort to investigate the performance of co-axial atomizers utilized in pharmaceutical tablet coating when atomizing common tablet coating solutions under typical processing conditions. In pharmaceutically relevant applications, the liquids being atomized are typically complex, non-Newtonian fluids which may contain polymers, surfactants and large concentrations of insoluble solids in suspension. The goal of this investigation is to produce a validated theoretical model capable making timely predictions of atomizer performance in pharmaceutical tablet coaters. The Rayleigh-Taylor model developed by Varga et al. has been extended to viscous and non-Newtonian fluids starting with the general dispersion relation developed by Joseph et al. The theoretical model is validated using droplet diameter data collected with Phase Doppler Particle Analysis. The primary output from the model is the Sauter Mean Diameter of the atomized droplets, which is shown to compare favorably with experimental data. Critical model parameters and plans for additional research are also identified.