Three-dimensional numerical study on hydrogen bubble growth at electrode

TL;DR

This study uses 3D numerical simulations to analyze hydrogen bubble growth and detachment at electrodes, providing insights into optimizing electrolysis efficiency through bubble behavior understanding.

Contribution

The paper introduces a detailed 3D simulation approach for bubble dynamics, validating results with experiments and analyzing effects of contact angle and nucleation sites.

Findings

Bubble growth follows diffusion-controlled scaling, with initial overprediction.

Nucleation site density influences gas transport and bubble coalescence.

Detachment radius correlates linearly with contact angle, highlighting surface tension effects.

Abstract

Three-dimensional direct numerical simulation of electrolysis is applied to investigate the growth and detachment of bubbles at electrodes. The moving gas-liquid interface is modeled employing the VOF-based method. To ensure the accuracy of the simulations, a mesh-independence study has been performed. The simulations include the growth phase of the bubbles, followed by their detachment from the electrode surface, and the results are validated with analytical models and experimental data. The bubble growth is diffusion-controlled, leading to the scaling \(R\propto t^{1/2}\), but our simulation overpredicts the growth exponent during the initial stage. We further demonstrate that the number of nucleation sites significantly affects gas transport, as quantified by the Sherwood number. The influences of contact angle and nucleation site on bubble detachment are also examined. The predicted detachment radius varies linearly with contact angle, consistent with Fritz's linear relation between the volume-equivalent radius and contact angle, confirming that the surface tension is the dominant attachment force. Finally, as the nucleation sites increase, the induced bubble coalescence accelerates the bubble detachment. Taken together, these findings give us valuable insights into improving gas bubble removal and enhancing overall electrolysis efficiency.