Ultrasonic dehydration of materials without liquid-vapor transition.

This study validates the mechanism of ultrasonic dehydration without transition of water into vapor. The process can be realized by cavitation dispersion of liquid initiated by collapse of cavitation bubbles of cylindrical shape formed in capillaries. The developed mathematical model considers the complete life cycle of cavitation bubbles, encompassing three stages: slow growth, rapid expansion with deformation, and collapse. The optimum range of sound pressure level from 150 dB (critical level) to 170 (limit level) at which cavitation dispersion of liquid from capillaries takes place has been determined. The optimum sample size corresponding to the ultrasonic wavelength in gas, at which the dehydrated productivity is maximized, has been determined. The mechanism of ultrasonic dispersion of liquid during drying was confirmed by experiments. Practical implementation of ultrasonic drying of food products (carrots) confirmed effectiveness of implementation of dehydration mechanism and provided a reduction of drying time by 1.9 times with a reduction of power consumption by 1.7 times. [ABSTRACT FROM AUTHOR]