Work

Effect of pressure and thermal management on stray currents in alkaline water electrolyser stacks

Year: 2026

Type: article

Abstract: Stray currents bypassing the active area through ports and manifolds decrease current efficiency in industrial alkaline water electrolysers (AWEs). The coupled electrical–thermal model for a 163-cell industrial stack quantifies how operating pressure and the inlet–outlet temperature difference ( Δ T ) affect stray-current losses, their inlet/outlet distribution, and current efficiency. Pressure influences conductivity through changes in void fraction and water-vapour formation. Thermal balance determines the inlet temperature and electrolyte flow rate to achieve a set Δ T . Increasing pressure compresses bubbles, reduces water-vapour mass flow, and increases outlet-side conductivity. This raises outlet-side stray-current losses, while the inlet-side share remains nearly constant. Raising Δ T lowers the inlet temperature and reduces the flow rate required to meet the outlet-temperature constraint, decreasing ionic conductivity at both the inlet and outlet. Thus, lowering pressure at fixed Δ T and raising Δ T at fixed pressure both reduce stray-current losses. Adjusting the electrolyte flow with input current can further suppress them. However, if the outlet void fraction saturates at 75 % (e.g., due to rapid gas removal), reducing pressure provides little additional benefit. In this case, the current-efficiency plateau occurs near 10 bar(a). This analysis highlights the need to manage both pressure and Δ T to design and control high-efficiency AWE stacks.

Source: Journal of Power Sources

DOI: 10.1016/j.jpowsour.2026.240148