Cavitational Activity in the Reactors

There exists a wide distribution of cavitational activity in the sonoreactor with the maximum intensity observed just above the center of the transducer (for the standard arrangements such as ultrasonic horn/bath). The intensity varies both axially as well as in the radial direction with decreasing trends as we go away from the transducer 

Immersion-type transducers are the poorest, when scaleup possibilities are considered, though very high intensities (pressures of the order of a few thousand atmospheres) are observed very near to the horn. The intensity decreases exponentially as one moves away from the horn and vanishes at a distance of as low as 1 cm away as observed by Chivate and Pandit (1995). It should be also noted that the active zone in the case of an ultrasonic horn also depends on the maximum power input to the equipment 

To increase the active zones existing in the reactor, one can easily modify the position of the transducers (if multiple transducers have been used, which is likely to be the case at large-scale operation due to the fact that it is quite difficult to successfully operate a single transducer with very high power and frequency due to limitations in the material of construction of the transducers) so that the wave patterns generated by the individual transducers 

The work of Keil and coworkers (Keil and Dahnke, 1996, Keil and Dahnke, 1997a, 1997b, Dahnke and Keil, 1998a, 

The design used by Dahlem et al. (1998,1999) also needs a special mention here. 

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Overall, it can be summarized that, use of multiple frequency irradiations based on the use of multiple transducers gives much higher cavitational activity in the reactor and hence enhanced results. It is also recommended that a combination of low frequency irradiation (typically 20 kHz) with other frequencies in the range of 50-200 kHz should be used for obtaining maximum benefits from the cavitational reactors. 

Geometry of the reactor Number of cavitational events and cavitational activity distribution Higher number of transducers of optimum shape so as to achieve uniform cavitational activity in the reactor... 

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