ABSTRACT
Microwave (MW) and MW-hybrid dryer systems are alternatives to conventional hot-air dryers. Moisture content is the most important dryer output variable and can be measured using a sensor system or electronic balances integrated into the dryer control system. Temperature or moisture content can be a measured variable for a feedback loop control system to better automate dryer operation. The chapter focuses on considerations and design criteria for control of MW drying systems. During the drying of an agricultural product, the most important factor is the limit value of the product temperature, beyond which the product could be damaged. For this reason, the automatic control of MW drying should protect the drying product against damage due to exposure to high temperatures, which causes stress cracks in the matrix. The distributed parameter model is preferable in modeling the process of heat and mass transfer in capillary porous bodies because it allows for estimation of the effects of different parameters of drying process.
