Comparative Numerical Study of Freeze Drying of Solution and Spray-frozen Particles in Trays and Vials

Abstract

A prototype spray freeze dryer was constructed to produce microsized porous particles for pulmonary inhalable drugs by incorporating a spray freezing module into a commercial batch-type freeze dryer. A preliminary experiment of the spray freeze drying of an egg albumin solution was conducted and the physical appearance of the produced particles was examined qualitatively. Based on the experimental observation, a numerical model was developed and parametric studies were conducted to investigate the heat and mass transfer characteristics during the freeze drying of spray-frozen particles packed in trays and vials. The simulation results of particle-based products were compared with those of solution-based products to identify the difference in their freeze drying behavior. As a result, particle-based products were predicted to require longer primary drying time than solution-based products, mainly due to the reduction of heat and mass transfer capabilities and the development of a secondary dried layer near heat-supplying surfaces.

Notes

^a All properties are extracted from Sadikoglu and Liapis [8] and Sheehan and Liapis [9] except where indicated.