Characteristics of Drying due to Microwave Heating

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Microwave heating is one of the most Interesting methods for heating materials. In this report, the drying of water saturated packed bed and the heating of multi-layered packed beds by using microwave in rectangular wave guide has been investigated theoretically and experimentally.The results obtained here are summarlzed as follows ;(1)When microwave is directly applied to a high dielectric material, most of it is reflected on the surface. Setting a relatively low dielectric materials in front of a high dielectric material reduces to the reflection.(2)In heating of multi-layered packed beds, the reflection rate corresponding to the performance of the heating strongly depends on the dielectrisity and the thickness of the additiuonal material. The predicted results for the reflection rates of microwave and the temperature distributions In the sample are in agreement with the experimental results.(3)In drying due to microwave heating, the dry layer having a low dielectrisity acts as a layer of avoiding relrection and the temperature in the wet layer arizes and it in the dry layer drops as drying proceeds.(4)Comparing of the usual dring process using hot air, the drying due to microwave heating has the relatively uniform drying rate.