Effects of gas bubbles on the concentration profiles and conversion efficiency of three-dimensional packed-bed electrodes

摘要

The effects of evolving gas bubbles on the concentration profile and conversion efficiency of three-dimensional packed-bed electrode was simulated for the first time, taking account of material balance, bubble, ohmic, kinetic, and mass transfer effects. The model produced different dimensionless groups and parameters that control the behavior of the packed-bed electrode under potentiostatic conditions. The effects of the different groups on the conversion efficiency, concentration, polarization, and current profiles were studied. Higher conversion efficiency were obtained at higher values of ω $left( {omega = frac{{I_0 L}}{{nFDC_b }}} right)$ , lower values of δ $left( {delta = frac{{upsilon L}}{D}} right)$ and higher values of the bubble group, ξ ( $xi = frac{{upsilon gamma }}{{I_o }}$ ). Gas bubble formation retarded the operation at higher conversion efficiency. In presence of gas bubble, lower values of δ were required to obtain as much as conversion efficiency obtained when the gas bubble formation is absent. Also, the bubble formation retarded the operation at lower flow rates as it causes lower obtainable current and non-uniform distributions of the currents. A case study was introduced for understanding the separate important operating conditions, e.g., flow rate. Account of gas bubble effects on the concentration profiles for such system is crucial.