Abstract: External humidification for fuel and oxidant gases of PEMFC makes the system complicated, it is of practical interest to operate PEMFCs through self-humidification. The key to improve PEMFC performance of self-humidification operation is to maintain the polymer electrolyte membrane adequately hydrated. Thus, self-humidifying membrane electrode assembly (MEA) is an effective way. In this paper, a mathematical model of water transport balance was developed to predict water content distribution in proton exchange membrane, and further study the feasibility and stability of self-humidification operation. Numerical analysis illustrated that the membrane was thin enough to satisfy the demand of hydration. In order to maintain the membrane hydrated well and achieve good performance of PEMFC, cell temperature and operating pressure were set 60℃ and 0.15 MPa, air stoichiometry was increased to 1.8. Based on these conditions, the performance of PEMFC showed a little difference between self-humidification and full-humidification. But there was a large gap compared to optimized full-humidification. It was applicable for self-humidificaiton to simplify the structure and reduce the cost, mass and complexities of PEMFC. But full humidification cannot be replaced completely.

Key words: fuel cell, self-humidification, proton exchange membrane, water transport, numerical analysis

摘要： 增湿及水管理系统使得燃料电池系统结构复杂，质子交换膜燃料电池（proton exchange membrane fuel cell，PEMFC）自增湿操作在实用化方面逐渐引起研究者的兴趣。提高PEMFC自增湿性能的关键在于对生成水的有效管理，保证质子交换膜的良好水合。实践证实采用自增湿膜电极组件是一个有效途径。本文建立催化层中增加保水层的水传递平衡模型预测膜中水的分布，考察自增湿操作的可行性和稳定性。数值分析表明：只有低于50 mm（如Nafion112）的薄膜能满足电池自增湿膜水合的要求。保证膜水合性能和电池操作稳定性的电池温度为60℃，操作压力为0.15 MPa，阴极气体过量系数可以增大到1.8。在上述操作条件下，电池自增湿性能与饱和增湿有可比性，与饱和增湿最佳条件有差距。因此PEMFC自增湿性能在综合考虑降低成本和费用，简化结构和操作时具有可行性，但不能替代增湿操作。

关键词: 燃料电池, 自增湿, 质子交换膜, 水传递, 数值分析