Plate structure design guideline for commercial alkaline water electrolyzers (AWEs) with improved liquid flow uniformity: Multi-scale quantitative criteria and experimental validation

Alkaline water electrolyzers (AWEs) holds great promise for large-scale green hydrogen production, but its commercialization is impeded by high electrical energy costs. Improving flow uniformity in AWEs is crucial to reduce energy consumption, necessitating optimized plate structure designs. Regrettably, the quantitative investigation of flow uniformity in electrolyzers is rare, due to the complex flow behavior. As a consequence, the existing designs primarily rely on empirical knowledge, lacking an efficient and systematic design guidance. This study establishes a general plate structure design strategy for commercial AWEs by introducing quantitative criteria for flow uniformity in multi-scale. The strategy comprises four steps: 1) single unit design to improve lateral liquid distribution, 2) evaluation of velocity magnitude discrepancy at horizontal sections, 3) flow behavior prediction by RTD analysis, and 4) validation through performance test. The strategy incorporates three quantitative parameters φ, δ, θ to evaluate the performance in three different levels. Two novel designs, namely, the rhombus and wedge electrolyzers are proposed to demonstrate the design strategy. Additionally, an in-situ electrolysis visualization/performance test platform is developed to vividly depict the gas-liquid flow during electrolysis and validate the effectiveness of our design guidelines. The proposed design guideline provides step-by-step guidance for the plate structure design of future high-performance commercial AWEs.