Thermoelectromagnetic coupling in microwave freeze-drying
2007
Heng, S | Hongmei, ZH | Haidong, F | Lie, Xu
A coupled thermoelectromagnetic model of microwave freeze-drying was developed by introducing the reflection coefficient method of the electromagnetic theory into the sublimation-condensation model, to describe the coupling between the electromagnetic field strength distribution and the heat and mass transfer in microwave freeze-drying. The experiments of beef were provided and the good agreement between the predicted and experimental results validates the model. The variations of the field strength, the temperature and the moisture content distributions during the microwave freeze-drying process were discussed based on the model. The simulated results show that the microwave distribution in the cavity is a moving standing wave and that the actual field strength inside the material is less than that in the cavity. The nonuniform heating of the microwave will increase either the temperature in the dried region or the temperature in the frozen region, depending on the microwave input direction.
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