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Transport and fast dissolution of CO2 bubbles in realistic microfluidic flows: Transient dynamics and collective effects

par Sobac, Benjamin ;Haut, Benoît ;Kechadi, Mohammed ;Dehaeck, Sam ;Scheid, Benoît
Référence International journal of multiphase flow, 201, 105747
Publication Publié, 2026-07

Article révisé par les pairs

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Résumé :

We investigate the transport and rapid dissolution of carbon dioxide (CO2) bubbles in methanol within a horizontal circular microchannel operated under a pressure of 3 bar. This experimental configuration, featuring coaxial gas injection and high gas volume fractions, enables the observation of nearly the entire dissolution of individual spherical bubbles within the field of view. The vertical off-centering and progressive size reduction of the bubbles allow a broad exploration of key parameters such as bubble size, eccentricity, and inter-bubble distance. Unlike classical microfluidic studies focusing on isolated bubbles in fully developed flows, our system captures complex transient phenomena including initial bubble acceleration, lateral migration, and strong hydrodynamic interactions between closely spaced bubbles. We show that axial and vertical velocities significantly deviate from quasi-steady-state predictions, especially in the presence of confinement and collective effects. In contrast, the Sherwood number Sh remains well described by the theoretical scaling law Sh∝Pe(d∗)3, with Pe the Péclet number and d∗ the reduced bubble diameter, for bubbles near the microchannel centerline, highlighting the robustness of boundary-layer-based models. Importantly, our experiments reach an unprecedented range of high Péclet numbers for microfluidics (Pe∈[8700−52,000]), providing the first direct experimental access to high-dissolution regimes, and reveal that transient and collective events can enhance the overall mass transfer by about 8% and up to 60% compared to isolated bubbles. These findings demonstrate the importance of accounting for such dynamics when designing efficient gas-liquid absorption processes, and provide a detailed experimental framework for future model validation under realistic microfluidic conditions, while opening new perspectives for optimizing mass transfer strategies.