ABSTRACT
Microwave drying has been applied for example in food engineering, pharmaceuticals and in the production of building materials. Microwave drying is a special case of dielectric heating, which is the absorption of energy in a material with a very small but finite electrical conductivity. This chapter presents the feedback control design studies. In order to prevent the formation of temperature profiles, which may result in damage of the solid structure or the inactivation of ingredients, feedback control of the heat transfer by microwaves in thermally thick solids is required. The chapter then provides a nonlinear feedback controller for a process model of average moisture content and product temperature. Thermal treatment is a basic operation in solid and fluid processing; either as a stand-alone operation, for example in curing, thawing or pasteurisation, or as part of combined heat and mass transfer processes, for example drying of food, pharmaceuticals, or building material.
