A distributed parameter model for particles in the spray drying process

A multicomponent particle drying model has been developed to describe the compositions and temperatures of spray-dried particles using distributed drying kinetics. This means that component migration is expected to occur within the particles, thus temperature and moisture content gradients through the particles are present and might not be uniform. Particles are divided into a number of shells and may be spray dried from a solution of several solutes dissolved in water, such as sugars and proteins. The model simulates the drying kinetics within a concurrent spray dryer and also accounts for the effects of the solubilities of the solids, as well as surface activity of the components. The model has been successfully compared with an analytical solution for evaporation alone, to test the modelling of the external heat and mass-transfer processes. The model has also been compared with an analytical solution for internal diffusion in a sphere, which has tested the modelling of the internal heat and mass-transfer processes.