Dielectric microwave-assisted drying

To date, only microwave hot-air dryers used principally in flnish drying processes to level-off the moisture content in pasta, crackers or chips, and microwave vacuum dryers custom-made to specific product requirements, are available commercially (Ratti, 2008). Good microwave-assisted drying equipment should have a uniform distribution of the microwave field, provide a movement of the material to be dried, keep the microwave field strength in the drying chamber lower than the dielectric breakdovm strength, and possess an economic dehumidification system. 

Consequently, we consider that the industrial scale technological management of microwave assisted chemical reaction is no compatible with batch reactors coupled with multimode applicators. Some typical processes with a systematic decrease of the dielectric losses of the concerned reactant, such as filtration and drying of mineral or pharmaceutical powders are compatible with multimode applicators. To our knowledge, the only industrial batch microwave device is the microwave variant of the Turbosphere ( all in one solution mixer/granulator/dryer designed by Moritz... 

Subsequent to freeze stabilization, wet books can be thawed and air dried with or without interleaving or they can be vacuum dried in heated chambers (5). The moisture in frozen books can be sublimed by freeze drying (10) or removed by a vacuum/thaw/outgassing process (8), with microwave energy (6, 14), with dielectric energy (6), or by solvent extraction with or without vacuum assistance (5). 

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