The effects of sublimation-condensation region on heat and mass transfer during microwave freeze drying

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 free;e-drying rests of unsaturated beef are carried out. The experimental results show that the drying rime 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.