Current literature on simulation of drying processes can be divided into lumped parameter approaches, consisting of the Characteristic Drying Curve and the Reaction Engineering approaches, and distributed parameter approaches. Current attempts to simulate the particle drying processes have not captured the processes of diffusion for both the solvent and the solutes. Thus a new distributed parameter model that allows for multicomponent diffusion is needed.

This multicomponent model has been developed to describe the compositions and temperatures of spray-dried particles using distributed drying kinetics. This means that component migration is assumed to occur within the particles, thus temperature and moisture content gradients through the particles are present, and the temperatures and compositions may not be uniform. Particles are divided into a number of shells and are 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 the surface activity of the components.