Speaker
Description
Green hydrogen, produced through water electrolysis powered by renewable energy sources, has emerged as promising route for industrial decarbonization and energy storage. Electrolyzers are essential units for this process, as they split water into hydrogen and oxygen using clean electricity. Among different types of electrolysis technologies, Proton Exchange Membrane (PEM) electrolyzers are particularly attractive due to their ability to operate at high current densities, generate hydrogen with high purity and efficiency, and their fast dynamic response. Despite significant technological progress, their commercialization and durability are still limited, and overall performance is strongly influenced by two-phase flow transport phenomena. On the anode side, oxygen gas evolves within the catalyst layer and flows concurrently with liquid water through porous transport layer (PTL) and flow channels. Inefficient gas removal leads to pore blockage, restricting water access to catalyst layer, increasing mass transport losses, and reducing conversion. Additionally, gas in the flow channels may form slugs, which obstruct the channel cross section and induce pressure drop, decreasing performance. For these reasons, detailed pore-scale and channel-scale understanding of these coupled gas-liquid transport mechanisms is essential for improving efficiency, durability, and scalability.
To investigate pore-scale gas-liquid transport, a two-dimensional numerical model was developed using a randomly distributed array of circular fibers to represent the cross-section of a realistic PTL microporous structure. This approach lowers computational cost and enables examination of the underlying transport physics before extending the analysis to more complex domains. Computational geometry consists of a porous layer connected to an adjacent flow channel, allowing the study of bubble emergence in the PTL and its interaction with the channel region. Gas-liquid interface evolution, bubble growth, and breakthrough were resolved using the Volume of Fluid method in OpenFOAM. Parametric cases were evaluated by varying inlet flow rates and surface wettability. The 2D simulations are complemented by preliminary simplified 3D studies to examine the influence of the third spatial dimension on bubble distribution, transport pathways, and surface coverage patterns.
Across all conditions, the simulations reveal that oxygen moves through the PTL by forming irregular, finger-like paths that gradually connect and create one or two main channels as the gas approaches the flow channel. When breakthrough occurs, larger bubbles appear in the channel, can briefly form slug-type patterns, and induce a sudden local pressure drop. The pressure inside the PTL changes together with the gas paths: it increases in narrow throats during fingering and decreases as the bubble approaches detachment. Parametric studies indicate that gas transport in the PTL is governed by capillary forces. Wettability has a strong influence on the flow pattern: hydrophilic surfaces produce clearer and more confined gas pathways, whereas increasing hydrophobicity leads to wider throats, less distinct fingering, and gas advancing as broader connected regions. In contrast, changes in inlet water velocity influence the local flow around active fingers but do not significantly alter the overall gas pathway. Overall, this work discusses pore-scale gas transport and breakthrough mechanisms in PTLs, using a combined 2D-3D modeling framework to assess how dimensionality influences capillary-driven pathway formation.
| Country | Belgium |
|---|---|
| Student Awards | I would like to submit this presentation into the InterPore Journal Student Paper Award. |
| Acceptance of the Terms & Conditions | Click here to agree |
