Bubble Effects on the Solution IR Drop in a Vertical Electrolyzer Under Free and Forced Convection

Abstract

Effects of electrolytic bubbles on the IR drop of caustic soda solution in a vertical cell of one meter height were studied under both free and forced convection. Three pairs of Luggin-Haber probes were positioned near the anode and the cathode to determine the solution IR drop during electrolysis. A sectioned electrode having 10 segments was employed to obtain the current distribution from the bottom to the top of cell. The superficial resistivity of the solution containing gas bubbles agreed well with the Bruggemann equation.The solution IR drop decreased significantly when adequate conditions or cell geometry for solution circulation were provided. The anode-to-cathode gap was found to be the most important parameter for reduction of the solution IR drop in a vertical cell.

Mass transport and active area of porous Pt/Ti electrodes for the Zn-Ce redox flow battery determined from limiting current measurements

“…Small bubbles, are observed in the positive half-cell during the battery charge and in larger quantities during discharge. Bubbles can produce significant ohmic drops in flow reactors by increasing the resistivity of the electrolyte [48] and by shielding the electrode surface [49]. This would be consistent with the fact that no large potential losses were predicted for an ideal Zn-Ce model cell with planar electrodes under the assumption of no OER [12].…”

Electrochemical redox processes involving soluble cerium species

“…These effects are more evident in sulfuric acid, where the variation in the formal potential for The dependence of the thermodynamics and kinetics of the cerium redox reaction on its associated ligand chemistry and ligand reorganization is a central topic in the review of the electrochemistry of cerium organic complexes by Piro et al [67] Ce(IV) does not seem to respond in the same way as transition metals and actinides to organic ligands commonly used to stabilize higher oxidation states. This might suggest restrictions in the use of complexing agents/additives or Ce-based polyoxometalates in industrial electrolytes.…”

“…The oxidation of Ce(III) is affected the most and this can produce efficiency losses and limit the operational current density in reactors, particularly when planar electrodes are used instead of threedimensional ones [33,65,66]. Low electrolyte flow rates can also allow gas bubbles to remain near the electrode thus increasing the resistivity of the electrolyte near its surface [67].…”

Modelling the effects of oxygen evolution in the all-vanadium redox flow battery

“…Side reactions consume a portion of the current density applied to the cell and, therefore, lower its efficiency. Bubble formation reduces the electrolyte volume in the electrodes, lowering the active surface area for reaction and affecting the bulk transport coefficients of the reactants and the bulk permeability of the porous electrode [6][7][8][9]. It is important to understand the extent of performance degradation and the conditions under which performance is severe affected.…”