Exploratory research on bubbles migration behavior and mass transfer capacity evaluation of proton exchange membrane water electrolyzer based on a volume of fluid-coupled electrochemical model

Abstract

The proton exchange membrane water electrolyzer (PEMWE) is a promising hydrogen production technology from renewable energy. Efficient bubble management is crucial to enhance energy conversion efficiency. In this study, a volume of fluid (VOF)-coupled electrochemical model was developed to investigate the effect of various parameters on bubble migration behavior and mass transfer capacity in a PEMWE. The results showed that plug flow was effective in reducing the shielding effect of bubbles on the bottom wall, whereas film and wave flows led to water starvation and PEMWE performance degradation. High outlet pressure and inlet velocity should be avoided at high current density to reduce the bubble coverage on the bottom wall. To prevent the formation of films and wave flows that decrease the mass transfer capacity of PEMWE, it is recommended to maintain a minimum depth of 1 mm in the anode channel (ACH). The hydrophobic ACH wall is beneficial to reduce the bubble coverage on the bottom wall. Reducing the contact angle of the anode porous transport layer (APTL) from 90° to 50° leads to a 42.9% decrease in bubble coverage on the bottom wall at 3 A/cm2 due to facilitated bubble detachment and increased plug flow height. In addition, the APTL contact angle showed the highest sensitivity in influencing the bubble coverage on the bottom wall. These finding provide valuable guidance for the design and operation of PEMWE.