Engineering design method for cavitational reactors: I. Sonochemical reactors

Abstract

High pressures and temperatures generated during the cavitation process are now considered responsible for the observed physical and chemical transformations using ultrasound irradiation. Effects of various operating parameters reported here include the frequency, the intensity of ultrasound, and the initial nuclei sizes on the bubble dynamics, and hence the magnitude of pressure generated. Rigorous solutions of the Rayleigh-Plesset equation require considerable numerical skills and the results obtained depend on various assumptions. The Rayleigh-Plesset equation was solved numerically, and the results have been empirically correlated using easily measurable global parameters in a sonochemical reactor. Liquid-phase compressibility effects were also considered. These considerations resulted in a criterion for critical ultrasound intensity, which if not considered properly can lead to overdesign or underdesign. A sound heuristic correlation, developed for the prediction of the pressure pulse generated as a function of initial nuclei sizes, frequency, and intensity of ultrasound, is valid not only over the entire range of operating parameters commonly used but also in the design procedure of sonochemical reactors with great confidence.