High-intensity sound

When a liquid is exposed to ultrasonic irradiation, a variety of phenomena can be observed originating from streaming and cavitation. High intensity sounds in liquids are accompanied by wave radiation pressure which results in steady-state... 

TLS have been probed effectively in ultrasonic experiments. An interesting strategy is used in these measurements. This is the so-called hole burning technique. When the intensity of the acoustic pulse is sufficiently high, the two states in TLS become equally populated and therefore the absorption from the acoustic field becomes saturated. As a result, the subsequent pulse suffers a reduced attenuation. Thus the high intensity sound pulse has burnt a hole in the occupation number at an energy, E =hco with a width Aa>. This is illustrated in Figure 9.06 for the... 

It is reasonable to assume that pressure fluctuation caused by sound waves disrupt the boundary layer at the solid or liquid surface, so they should affect the interphase transfer rates and therefore accelerate drying rates. In fact, a substantial decrease (up to 15%) in the boundary layer thickness has been found when conventional spray-drying of blood plasma was complemented by the high-intensity sound at / = 15 kHz and I = 155 dB (Zayas and Pento, 1975). 

The major limitation of rotary dryers is the relatively low volumetric load ratio of the drum, which typically ranges from 3% to 16%. Because sound energy is absorbed in the bulk of particulates, it is difficult to secure the efficient use of high-intensity sound energy in large rotary dryers. Much better energy utilization is in the case of spray dryers since sonic irradiation intensifies heat and mass transfer but also enhances Uquid atomization (see Figure 13.9). 

Heterogeneous sonochemistry The use of high-intensity sound or ultrasound to alter chemical reactions in a two-phase system, usually a liquid and a solid. 

Sonochemistry The use of high-intensity sound or ultrasound to alter chemical reactions. 

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