|Title||Vacuolenvorming bij het verstuivingsdrogen|
|Source||University. Promotor(en): E.A. Vos. - Wageningen : Pudoc - ISBN 9789022004500|
|Publication type||Dissertation, internally prepared|
|Keyword(s)||melkpoeder - sproeidroging - vloeistofmechanica - gassen - vloeistoffen (liquids) - vloeistoffen (fluids) - mengsels - stroming - dried milk - spray drying - fluid mechanics - gases - liquids - fluids - mixtures - flow|
Experiments with a pilot spray drier showed that vacuoles in spray-powder particles originate from air bubbles. These are dispersed in the liquid during spraying, before actual atomization. During drying, the air bubbles expand as a result of gradual solidification of the droplet surface ('case hardening') before drying is complete. The vacuole volume is governed by the degree of air incorporation (related to type and design of atomizer and properties of the feed liquid) and the bubble expansion (related, for instance, to inlet air temperature).
Vacuoles do not develop as a result of spontaneous boiling phenomena. Vacuole-free powders can be produced by replacing the air in the atomizer by steam.