The sublimation-condensation model, developed for freeze drying of unsaturated porous media in the author’s previous work, is analyzed numerically. The moisture redistribution in the sublimation-condensation region is taken into account in this model. The calculations show that the saturation of ice in the sublimation-condensation region will obviously decrease, and its effects on heat and mass transfer cannot be neglected for microwave freeze-drying of unsaturated porous media. The microwave freeze-drying tests of unsaturated beef are carried out. The experimental results show that the drying time is approximately proportional to the initial saturation of beef. Moreover the sublimation-condensation model is validated by the experimental results. These results show that the sublimation-condensation model agrees better with experimental results than the sublimation interface model.

Issue Section:
Phase Change and Multiphase Heat Transfer
Keywords:
Mass Transfer, Phase-Change Phenomena, Porous Media
Topics:
Condensation, Drying, Heat, Mass transfer, Microwaves, Porous materials
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