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 solidliquid 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 solidliquid 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.