A GEOMETRICAL CONFIGURATION AND ITS EFFECT ON THE PERFORMANCE OF AN ELECTROCHEMICAL CELL UNDER FREE CONVECTION
WATHEQ NASER HUSSEIN
Babylon University, College of Engineering/ALMusayab, Iraq Email: wathq777@yahoo.com











Abstract The effect of positioning or location of the cathode electrode with respect to the surface margin of the electrodeposition electrolyte solution under free convection was numerically studied. The importance of such study arises from the fact that there is no study, according to the author s knowledge regarding the effect of electrode positioning (depth effect) and its effect on the current distribution and on the free convection (absence of forced convection) hence, its effect on mass transfer, that highly appears in the industrial application. It was shown that positioning of cathode near the surface of the solution gave bad results of deposits distribution while moving it downward has comparable results to that when the electrodes are in the middle of the electrolyte. Accordingly, the best configuration was achieved when the cathode location approximately is in the middle of the electrolyte with applied currents-as in this study of about 4.6 mA/cm2-. According to this study, it was found that there was no effect of free convection on the mass transfer or on the flux of Cu+2 ions and the main contributed mechanism is the diffusion one. Keywords: Comsol, Concentration distribution, Current distribution, Electrodeposition, Electrode positioning, Natural convection.
A Geometrical Configuration and its Effect on the Performance . . . . 3433


Journal of Engineering Science and Technology October 2018, Vol. 13(10)

1. Introduction Electrochemical process is affected by the hydrodynamics of the system through variation of the mass transfer of the process. An electrochemical process works either without forced convection or with. The external stirring is obtained when the work is allowed to move while the electrolyte or the solution is still as in the rotating cylinders or discs stirring, pumping or vice versa, etc. [1, 2]. According to Donahue [1], in the absence of forced convection, an enhancement of the rate of transport is possible by some sort of convective flow. Volgin and Davidov [2], during electrolysis at an electrode, the density and viscosity in the vicinity of the electrode can change substantially from those in the bulk of the solution. For example, during dissolution of a metal at high rates, the solution in the vicinity of the anode will be enriched with metallic ions with a resultant increase of the density of the fluid near the anode. In the presence of a gravitational field, the solution at a vertical anode will tend to fall due to this increased density. As the solution falls, it will move parallel to the electrode face and cause of flow of solution with a finite velocity. This flow tends to enhance the rate of material transport when compared to molecular diffusion. While a node process is of considerable interest in electrochemical engineering, many properties of the system such as degree of supersaturation of the anolyte, etc., make a quantitative description virtually impossible. Some of the related relations with deep analysis can be found elsewhere [3, 4]. Wagner [5] reported the importance of free convection effect on the hydrodynamic and since then numerous papers were issued regarding such importance [6-9]. There are many theoretical and numerical studies on the current distribution were reported in various electrochemical systems such as the rotating electrode disk [10, 11] and other configurations [12-14]. Current distribution is very important, especially in the electrodeposition process where it gives how the uniformity of deposits will be [15-18]. As stated