Coupled simulation of bubbles behavior and ion transport and reaction on alkaline water electrolysis

Abstract

In recent years, alkaline water electrolysis is receiving much attention on environmental issues because of hydrogen production using renewable energy. However, it is necessary to enhance the efficiency of electrolysis. One of the main causes that have effect on efficiency of alkaline water electrolysis is presence of bubbles in electrolyte. It is important to investigate the relation between bubbles behavior and efficiency of alkaline water electrolysis system. In this study, the calculation model to realize coupled simulation of ion transport, electrochemical reaction and bubbles behavior is developed and the impact of convection induced by bubbles on alkaline water electrolysis is investigated by numerical simulation. As a result, it is found that convection induced by bubbles has impact on mass transport around anode and has an effect on the efficiency of alkaline water electrolysis. Convection induced by bubbles in the vicinity of anode has an effect on ion transport to anode and anodic concentration overpotential. However, as bubbles depart from anode, this effect becomes small because convection removes ion from anode. Moreover, convection induced by bubbles shortens ion transport pass between electrodes and has an effect on ohmic loss.

Keywords

• alkaline water electrolysys
• ion transport
• bubble behavior
• numerical simulation
• hydrogen energy