Abstract Techniques for evaluating water management are critical to diagnose the performance of polymer electrolyte membrane fuel cells (PEMFCs). Acoustic emission as a function of polarisation (AEfP) has been recently introduced as a non-invasive, non-destructive method to analyse the water generation and removal inside a PEMFC during polarisation. AEfP was shown to provide unique insight into water management within a conventional PEMFC and correlating it to cell performance. Here, AEfP is used to characterise the performance of fractal PEMFCs by evaluating the hydration conditions inside them. This is achieved by probing the water dynamics inside two different fractal flow-field based PEMFCs, namely 1-way and 2-way fractal PEMFCs, and measuring the corresponding acoustic activity generated from them. AEfP is performed on the fractal PEMFCs under relatively humid (70% RH) and fully humidified (100% RH) reactant relative humidity (RH) conditions. Flooding in the 2-way fractal PEMFC, as opposed to the 1-way fractal PEMFC, is demonstrated under different operating conditions by the relatively higher acoustic activity it generates. Corroborating evidence of flooding in the 2-way fractal flow-field under different conditions is provided by its polarisation curves, impedance tests and galvanostatic (current hold) measurements.

中文翻译：

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使用声发射分析的分形流场聚合物电解质膜燃料电池的水合状态诊断

摘要 评估水管理的技术对于诊断聚合物电解质膜燃料电池 (PEMFC) 的性能至关重要。作为极化函数的声发射 (AEfP) 最近被引入作为一种非侵入性、非破坏性方法来分析极化期间 PEMFC 内部的水生成和去除。AEfP 被证明可以提供对传统 PEMFC 内水管理的独特见解，并将其与电池性能相关联。在这里，AEfP 用于通过评估分形 PEMFC 内部的水化条件来表征分形 PEMFC 的性能。这是通过探测两种不同的基于分形流场的 PEMFC（即 1 路和 2 路分形 PEMFC）内部的水动力学，并测量它们产生的相应声学活动来实现的。AEfP 是在相对潮湿 (70% RH) 和完全加湿 (100% RH) 反应物相对湿度 (RH) 条件下对分形 PEMFC 进行的。与 1 路分形 PEMFC 不同，2 路分形 PEMFC 中的泛滥在不同的操作条件下通过它产生的相对较高的声学活动来证明。通过极化曲线、阻抗测试和恒电流（电流保持）测量提供了不同条件下 2 向分形流场中洪水的确凿证据。