Bubble dynamics in alkaline water electrolysis: optical measurements of local void fraction and generated volume flow
Franz J, Hoffmann J, Qin AC, Etzold B, Dreizler A (2027)
Publication Type: Journal article
Publication year: 2027
Journal
Book Volume: 427
Article Number: 139850
DOI: 10.1016/j.fuel.2026.139850
Abstract
During alkaline water electrolysis, gas-evolving reactions generate bubbles that contribute to ohmic losses and an increase in activation and concentration overpotentials affect cell efficiency. Building on prior studies of bubble behavior, this work introduces two new aspects: spatially resolved void fraction near the electrode surface and locally generated gas volume flow as an indicator of surface activity. Both quantities are correlated with measured bubble dynamics. To achieve this, the oxygen evolution reaction is studied on a vertical wire electrode using Laser-Marked Shadowgraphy over a wide current-density range and multiple heights. Statistical distributions of bubble position, size, and velocity are obtained, together with local void fraction and gas volume flow. Their dependence on current density and vertical position is analyzed. Results show that bubble size primarily governs void fraction and, thus, bubble-induced resistance. A feedback mechanism is observed in which bubble-induced electrolyte flow enhances bubble transport, while bubble–bubble interactions cause a slowdown at high current densities. Spatial variations in generated gas volume flow reveal inhomogeneous apparent surface activity linked to convective transport. Overall, the results demonstrate the interplay of bubble dynamics and the electrochemical process and underscore the need for quantitative, spatially resolved, and statistically converged data for bubble dynamics.
Authors with CRIS profile
Julia Hoffmann
Lehrstuhl für Power-to-X-Technologien
Alex Chuan Qin
Lehrstuhl für Power-to-X-Technologien
Bastian Etzold
Lehrstuhl für Power-to-X-Technologien
Involved external institutions
Germany (DE)How to cite
APA:
Franz, J., Hoffmann, J., Qin, A.C., Etzold, B., & Dreizler, A. (2027). Bubble dynamics in alkaline water electrolysis: optical measurements of local void fraction and generated volume flow. Fuel, 427. https://doi.org/10.1016/j.fuel.2026.139850
MLA:
Franz, Jonathan, et al. "Bubble dynamics in alkaline water electrolysis: optical measurements of local void fraction and generated volume flow." Fuel 427 (2027).
BibTeX: Download