Study of the influence of transducer-electrode and electrode-wall gaps on the acoustic field inside a sonoelectrochemical reactor by FEM simulations

Abstract

a b s t r a c tThe influence of transducer-electrode and electrode-wall gaps on the spatial distribution of the acoustic pressure inside a sonoelectrochemical reactor has been studied by employing a linear acoustics-based model accounting for vibrations of the reactor walls. A FEM (Finite Elements Method) software package was used in order to simulate the response curves of the system, the distribution of the acoustic pressure and the deformation of the surrounding walls. Attenuation of the acoustic energy in the liquid due to the presence of cavitating bubbles was introduced using an attenuation coefficient, enabling to study its influence in the available working frequency range of the ultrasonic transducer (19-21 kHz). Acoustic energy stored in the liquid was plotted as a function of frequency in order to obtain the response curves of the sonoelectrochemical system, exhibiting different resonance peaks for each studied configuration. The proper election of the reactor configuration and setting of the working frequency of the transducer allows the formation of pressure antinodes near the electrode favouring cavitation events in this zone, and helping to minimize the cavitation-induced erosion of the sonotrode commonly observed during experiments.

Numerical simulation of the nonlinear ultrasonic pressure wave propagation in a cavitating bubbly liquid inside a sonochemical reactor

“…Further, the zero flux boundary condition at the surfaces of the heaters and the sonoreactor include some basic assumptions. A comprehensive way to account for more realistic boundary conditions is the coupling of elastic deformation and the wave propagation as implemented succesfully in [48,49,50]. Finally, other numerical methods, such as, the finite element method (FEM), the boundary element method (BEM) or the finite volume method (FVM), may be employed to solve the Helmholtz equation in order to compare their convergence rates with the current numerical approach.…”

Simulations of a full sonoreactor accounting for cavitation

“…Most simulations rely on linear acoustic [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], which takes the form of an Helmholtz equation and can be easily solved by the finiteelements method (FEM). The main drawback of such an approach is that the effect of cavitation on the acoustic field is not accounted for, apart for some studies using an empirical attenuation coefficient.…”

Sonochemical techniques to degrade pharmaceutical organic pollutants

“…Ultrasonic transducers are designed to convert either mechanical or electrical energy into high-frequency sound, and there are three main types: gas driven, liquid driven, and electromechanical (Leong et al 2011;Tudela et al 2011). The most readily available experimental setup for carrying out sonochemical reactions is the electromechanical transducers, which is currently used not only at laboratory level but also on a larger scale (Compton et al 1997).…”