Comprehensive Analysis of Flow Dynamics and Pressure Variations in PEM Water Electrolyzers: Experimental and Computational Insights into Gas Diffusion Electrodes

Abstract

Polymer Electrolyte Membrane Water Electrolyzers (PEMWEs) can produce green hydrogen with zero emission with renewable energy sources integration. The gas diffusion electrodes (GDEs) are one of the main components of PEMWE. In this study, the flow behavior of GDEs for different patterns like square GDE (SGDE), circle GDE (CGDE), equilateral triangle GDE (ETGDE), and rhombic GDE (RGDE) was investigated numerically and experimentally for different flow rates at 100 mL min−1, 200 mL min−1, and 300 mL min−1. In pressure drop (ΔP) and flow visualization experiments, SGDE showed the best performance. Experimental results were compared with each other by validating them in the numerical analysis of multiphase flow conditions. As a result, at 100 mL min−1 flow rate, the flow is directed to the outlet side with 38.96 % less pressure loss in SGDE geometry. In flow visualization experiments, at 100 mL min−1 flow rate, SGDE geometry fills the cell faster than other GDE geometries by 0.437 sec. The results from the ex-situ ink test performance of the GDEs were confirmed in electrochemical single cell PEMWE tests via Pt coated GDEs. Furthermore, SGDE exhibited superior performance in thein-situtests. In the numerical calculation results, when 16 % porosity filter paper was examined, it was concluded that the SGDE geometry was 94.8 % rate successfully carried the liquid phase to all geometry. It is supposed that water transfer inside the cell may be improved by using an SGDE for the anode GDE, and the performance of PEMWE could be increased by providing faster delivery of the oxygen gas and excess water to the outside of the cell.