Modelling Convective Drying Kinetics And Surface Composition Of A Single Droplet

The surface composition of spray-dried powders is influenced by many factors, such as solid content and chemical composition of the feed solution, drying air condition, and so on. Recently, a multiscale approach that couples the macro continuum diffusion model with the micro molecular packing model has been developed in our group to predict the surface composition of spray-dried lactose-protein powders. In this work, this method is extended to take the feed composition into account. The solid content and composition of the feed solution play a significant role in the surface composition of dried powders. Detailed calculations for the lactose-protein systems have demonstrated that the surface coverage of protein is increased with the decrease of the feed solid content. Also, the influence of the initial droplet size and the detectable depth of X-ray photoelectron spectroscopy(XPS) on the surface composition are studied. All these investigations can help us understand the particle surface formation, and hence may guide quality-focused manufacturing of the final powder product.The reaction engineering approach(REA) is a semi-empirical model to study the droplet drying behavior, which has been used to predict drying kinetics of a variety of materials. The REA can accurately predict temperature and mass dynamics of a drying substance with different materials and at different drying conditions. We developed a MATLAB based tool for drying kinetics prediction with the REA model. Users can readily use this tool to investigate the drying of various materials without knowing the details of the REA method itself. The tool was successfully applied to the study of the drying of a hydrogel material.