Modeling Particle Formation at Spray Drying Using Population Balances

There have been several efforts to simulate the physical processes in a single droplet during spray drying in the last several years, but most of the models do not describe the solid formation in detail. In this work, the development of the microscopic solid structure in a droplet during spray drying is simulated. A radial-symmetric model of the droplet is used to simulate the mass and heat transport. The solid formation at every radial discretization point is obtained by the solution of population balances. This way, the distribution of the particle number density in the droplet depending on the macroscopic process parameters can be predicted. The model equations are solved in a normalized coordinate system to be able to describe the shrinkage of the droplet. The suitability of these population balances will also be discussed. For the validation, monodisperse single droplets consisting of a solution or suspension are dried with constant boundary conditions.