Different Characteristics of Bubbles in Different Types of Sonochemical Reactors

Computer simulations of bubble oscillations in water have revealed that characteristics of bubbles depend on types of sonochemical reactors. When the acoustic amplitude is large at 20 kHz, the bubble content when a bubble collapses is mostly water vapor and the temperature inside a bubble at the collapse is relatively low. On the other hand, when the acoustic amplitude is relatively low, the bubble content when a bubble collapses is mostly noncondensable gas and the bubble temperature is relatively high. In a horn-type sonochemical reactor, the former type of bubbles are dominant because many bubbles exist near the horn-tip where the acoustic amplitude is large, while in a standing-wave type reactor the latter type of bubbles are dominant because the primary Bjerknes force gathers bubbles at a region where acoustic amplitude is relatively low.