Turbulent Mass Transfer to a Rotating Cylinder in AC Electrolysis

Abstract

An experimental and theoretical investigation has been made for turbulent mass transfer to a rotating cylinder when sinusoidal alternating current (ac) together with a direct current (dc) component is used for the electrolysis. The investigation was made for a range of the Reynolds numbers from 1000 to 40,000 and ac frequencies from 10 to 400 Hz. The limiting ac current density corresponding to an instantaneous zero surface concentration and the phase shift between the applied ac and the periodic concentration overpotential wave were experimentally measured with a ferricyanide‐ferrocyanide redox system. The results were compared to the theoretical predictions using a film model. It is found that the ac mass transfer to the rotating cylinder can be correlated with a single variable, , called the dimensionless ac frequency. For the values of greater than 10, the limiting ac current density becomes proportional to , where is the dimensionless dc current density. The experimental data agreed with the theoretical predictions to within ±12% over a range of greater than 10 and less than 20,000.