Experiment and numerical simulation of heat and mass transfer during a spray freeze-drying process of ovalbumin in a tray

Spray freeze-drying is a promising technology for producing high-quality porous particles primarily for pharmaceutical uses. The advantages of freeze-drying in the production of pharmaceuticals and biomedical products, such as minimization of thermal and chemical degradation, retention of volatile components, preservation of high porosity, and a very low content of residual water after drying, are mostly retained in spray freeze-drying. In this study, we performed spray freeze-drying of a 3% (w/w) chicken egg ovalbumin solution in a tray with a batch-type spray freeze-dryer that we developed. The physical characteristics of the spray freeze-dried particles were qualitatively evaluated by means of scanning electron microscopy. The freeze-drying behavior of spray-frozen particles was experimentally investigated by measuring the histories of product temperatures and numerically studied by developing an analysis model based on the finite volume method in a fixed grid system.