Water Movement Direction through an Anion Exchange Membrane Fuel Cell Exerted By Gas Humidity and Flow Rate: A Simulation Study

The growing demand for clean energy generation has been urged due to the threat of climate change by greenhouse emissions (1 kg of CO 2 per 1 kW h of generated electricity). In 2021, the electricity generation rose to 1530 TW h, 62% coming from fossil fuels [1]. To lower this significant fossil fuels usage, the development and use of alternative energy sources and green fuels have reached a formidable level of interest. Renewable solar and wind energy sources are currently available; however, those appear to be limited by natural fluctuations in energy production relegated to day- and night-time wheatear or geographical regions [2]. Electrochemical energy storage and conversion technologies can be employed to minimize production variations as an alternative to this limitation. The anion-exchange membrane fuel cell (AEMFC) is an excellent alternative for energy generation due to its air CO 2 -free emissions, low-cost electrocatalyst used at the cathode, and industrial-scale membrane production [3]. The design of a fuel cell involves several tightly interrelated factors, such as electrode and membrane materials, reactor geometry, and characterization of the reaction environment in terms of the momentum, mass and heat transport, electrode kinetics, and current distribution, to find the best operational conditions to reach a suitable energy efficiency [4]. In either case, the present work deals with designing a hybrid flow-field single-fuel cell. The monopolar anode plate is a multiple-serpentine flow field that benefits the water drainage. On the other hand, the cathode plate is an interdigitated leaf-type flow field that might ensure an efficient gas reactant distribution over the entire electrode geometric area. A two-phase flow CFD simulation is performed to analyze the influence of the flow field patterns on the mass transport processes in the electrodes. Moreover, the water movement direction through the membrane as a function of the operational conditions is presented. The commercial code COMSOL Multiphysics was used to solve the transport equations through the finite element method. In the experimental field, the water movement direction between the anodic and cathodic sides shows the capability to favor the electro-osmotic drag (EOD) or the diffusion water transport mechanism under different gas flow rates and humidities, as shown in Figure 1a. Accordingly, the results demonstrated that the EOD predominance was promoted when low symmetric flow rates (