Water movement through an anion exchange membrane fuel cell (AEMFC): Influence of gas humidity and flow rate

• Published in: Applied energy 2022-10, Vol.324, p.119722, Article 119722
• Main Authors: León, María I., Valentín-Reyes, Jonathan, Romero-Castañón, Tatiana, Beltrán, José, Flores-Hernández, José Roberto, Nava, José L.
• Format: Article
• Language: English
• Subjects: Anion exchange membrane; anion-exchange membranes; anodes; cathodes; Electro-osmotic drag; electroosmosis; energy; Fuel cell; fuel cells; humidity; Interdigitated channel; temperature; Water diffusion
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2022.119722

•Electro-osmotic drag (EOD) and diffusion water transport through an anionic membrane.•50 cm2 electrode area in an AEMFC with interdigitated and serpentine flow fields.•EOD and diffusion dominance at low-symmetric and asymmetric flow rates.•Best power peak in diffusion dominated AEMFC, 63 mW cm−2 at unsaturated conditions.•Asymmetric-unsaturated flows suggest flooding alleviation with membrane hydration. The water movement between the anodic and cathodic sides of a fuel cell (AEMFCs) motivated the analysis of the effect exerted by the operational conditions on the water direction using a commercial anion exchange membrane (IONOMR®). This work shows the capability to favor the electro-osmotic drag (EOD) or the diffusion water transport mechanisms under different gas flow rates and humidities. Accordingly, the results demonstrated that the EOD predominance was promoted when low symmetric flow rates (125 cm3 min−1 for anode and cathode) were used in the AEMFC, suggesting membrane dehydration. On the contrary, the water diffusion dominance appears under asymmetric flow rates between anode and cathode (125 and 250 cm3 min−1, respectively); under these conditions, the membrane dehydration might be suppressed by anode flooding alleviation. The AEMFC performance was affected by the water transport mechanism, giving lower peak power densities for EOD-dominated systems (35.2 mW cm−2 at 60 °C) than those obtained by diffusion (62.8 mW cm−2 at 60 °C). The most suitable operating condition is under water-diffusion at non-saturated streams (below 65%), where a decrease in performance is experienced as the humidifier temperature increases from 60 °C to 80 °C (supersaturated flow), giving peak power densities of 62.8 and 3.7 mW cm−2, respectively.