Evaluation of Effective Diffusion Coefficient under Time-Varying Electromagnetic Force Imposition

Abstract

The mass transfer in the concentration boundary layer is often the rate-determining step for solid-liquid chemical reactions. Decreasing the concentration boundary layer thickness is essential to intensify the solid-liquid chemical reaction. Because convection contributes to decreasing the concentration boundary layer thickness, traditional methods excite a macro-scale flow in the bulk region. Since the concentration boundary layer exists in the velocity boundary layer near the solid-liquid interface, the traditional methods have limitation in enhancing the mass transfer. Based on this reason, the direct flow excitation near the solid-liquid interface by imposing an electromagnetic force was proposed. The aim of this research is to evaluate the effect of the time-varying electromagnetic force and its frequency on the mass transfer near the solid-liquid interface by evaluating the effective diffusion coefficient. The effective diffusion coefficient was evaluated under the imposition of a static electromagnetic force or a time-varying electromagnetic force with a frequency of 2 Hz or 6 Hz. The results found that by imposing the time-varying electromagnetic force, the mass transfer was enhanced compared to that under the imposition of the static electromagnetic force. The mass transfer was further enhanced by decreasing the time-varying electromagnetic force frequency.