Study on gas accumulation in polymer electrolyte membrane water electrolyzer considering two-phase flow

In this study, we analyze gas accumulation in a polymer electrolyte membrane water electrolyzer by considering two-phase flows in the porous transport layer on the anode and cathode sides. First, effect of mass flow rate on gas accumulation is analyzed. The transport of liquid water occurred differently on the anode and cathode sides. While the transport of liquid water on the anode side decreased in the high current density region, that on the cathode side increased with current density. The limiting current density increased by 1.2 A/cm² when the mass flow rate was increased. Next, we study the effect of contact angle of the porous transport layer. When the contact angle was decreased from 75° to 30°, gas saturation decreased by 0.04. The use of a hydrophilic porous layer on the cathode side, however, hindered the transport of liquid water into the channel because the porous transport layer tended to retain liquid water. Finally, we study the effect of porosity of the porous transport layer. When the porosity was 80%, the mass flow rate of liquid water into the porous layer was 0.1 g/s, and gas saturation was approximately 0.25 at 0.8 A/cm².