ABSTRACT
The aim of this chapter is to present the advantages of convective nonstationary (intermittent) drying of biological materials (fruits, vegetables) and engineering materials (wood, ceramics) enhanced with microwaves and/or ultrasound. The term “nonstationary” here means drying with periodically changeable parameters (air, temperature, and/or humidity). The drying time, quality of dried products, and energy consumption are examined at different schedules of intermittent drying. The acoustic emission method is applied to monitor online the material behavior and to detect the commencement of material cracking, and thus to find the moment at which the changes of drying conditions should be initiated. The mathematical model is developed to describe and imitate the intermittent drying kinetics determined experimentally. This model is used next for numerical calculation of the drying efficiency carried out in intermittent conditions. The benefits of nonstationary drying with respect to that leading in constant conditions were assessed-->. Such a formulated subject is a novelty in the area of drying.
