Description of an ultrasonic technology for food dehydration process intensification

Food dehydration processes assisted by power ultrasound constitute an efficient and green technology. In order to obtain good results with this technology it is necessary to take into account several aspects regarding the ultrasonic generation by a power ultrasonic transducer, the energy propagation in the fluid media and absorption in the samples. Ultrasonic waves produce different effects when propagating through a medium, like an increase in mass transport kinetics, and others related to the so called sponge effect and cavitation. This kind of process needs the whole system to work in a power regime. This may imply the appearance of non-linear effects in the transducer behavior and in the acoustic field generated inside the dehydration chamber. This paper describes this technology, paying special attention to the numerical design and the dynamic and modal characterization of the power ultrasonic transducer. As a conclusion, neither modal interaction nor any other non-linear effect, apart from a slight softening behavior, is expected when applying high power.