Pore Network Modeling of Nonisothermal Two-Phase Transport in the Anode of Proton Exchange Membrane Electrolyzers

The performance and durability of proton exchange membrane (PEM) electrolyzers are significantly influenced by a complex interplay process among two-phase transport and heat transfer within the anode porous transport layer (PTL) and the catalyst layer (CL). When bubbles form within the CL, they are then transported and trapped in the PTL, impeding water transport to the CL. These bubbles also create thermal barriers, resulting in uneven temperature distribution and localized hotspots within the membrane electrode assembly (MEA). To clarify these coupled processes in the anode, a triple-phase, nonisothermal pore network model is established for the anode PTL and CL. Temperature distributions for liquid and solid phases are initially determined, alongside dissolved oxygen concentration distributions. Oxygen formation and evolution at active sites with high dissolved oxygen concentrations and temperatures subsequently invade the CL and PTL, further influencing the heat transfer process. The formation of the gas phase increases the average temperature increase by 1.5 K in both liquid and solid phases. The maximum temperature increasement reaches about 7 K inside the CL, which occurs at an operating current density of 2000 mA cm–2. These findings offer valuable perspectives on the mechanism of the interaction between two-phase transport and heat transfer in the anode of PEM electrolyzers.