IDENTIFICATION OF REGIMES AND CONDITIONS FOR MOISTURE, REMOVAL FROM MATERIALS BY NONCONTACT EXPOSURE TO ULTRASONIC VIBRATIONS

The possibility of intensifying the drying of materials by noncontact ultrasonic action at a frequency of 22 kHz at sound pressure levels up to 175 dB has been studied. A signifi cant increase in the rate of drying materials in the range of sound pressure levels from 160 to 165 dB was revealed, which is due to the implementation of the mechanisms of moisture removal from a dried material without a phase transition, i.e., due to the dispersion of free moisture from the surface of the material by ultrasonic vibrations. In this case, the time of drying the material is reduced by more than 40% compared with its drying by a conventional dryer, with an ultrasonic device consuming no more than 25% of the electric power of a conventional dryer required for drying a material weighing 0.25 kg. Further acceleration of the process is not always advisable, since the reduction of the time of drying the material by 57.1% on exposure to a sound pressure of 175 dB requires more than three times increase in energy consumption (82% of the total electric power of the dryer) for creating ultrasonic vibrations
   
Author:  A. V. Shalunov ,  V. N. Khmelev ,  S. A. Terent′ev ,  V. A. Nesterov
Keywords:  drying, dehydration, ultrasound, sound pressure level, intensifi cation of drying, thermolabile materials
Page:  909