Numerical investigation of sonochemical production in a single bubble under dual-frequency acoustic excitation

Abstract

A numerical computation study about sonochemical activity of an oxygen bubble oscillations in a dual-frequency acoustic field is presented in this paper. The variation of excitation frequency causes the change of magnitude and duration of pressure acting on the bubble, affecting the instantaneous bubble radius, internal bubble temperature as well as chemical reactions. The numerical results indicate the formation of O2, HO2•, •OH, H•, O, H2 and H2O2 in an O2 bubble during collapse phase. The main oxidant is •OH radical. The influence of several parameters (e.g. couples of frequencies, the total pressure amplitude and the ratio of pressure amplitudes of the two waves) on the molar yields of the oxidants is analyzed. There is an optimum bubble collapse temperature (around 5648 K) for the •OH production. Moreover, the corresponding frequency intervals of enhanced effect and weakened effect under different coupled frequencies (i.e. 40, 140, 213, 355 and 515 kHz) are also investigated.

Ammonia production by microbubbles: A theoretical analysis of achievable energy intensity

“…During their oscillation, the internal temperature can reach several thousands of Kelvin for sufficiently high irradiation intensity. Such an extreme condition induces chemical reactions, which have been extensively studied in the last decades both experimentally [12] , [13] , [14] , [15] , [16] , [17] , [18] and numerically [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] for various combinations of liquid–gas compositions with different levels of modelling complexities [31] , [32] , [33] , [34] , [35] . The chemical yield depends on the composition of the bubble interior: initial gas content and mass transfer via evaporation/condensation or diffusion.…”