PEMFC中液态水沿程分布的机理研究

Investigation into water distribution along flow channel in PEMFC

通过分析流道和扩散层中的压力损失,并根据理想气体状态方程,得出了沿流道方向气体总压力以及水蒸气分压力沿程分布的表达式.根据液滴生成的机理分析,得出了PEMFC阴、阳两极扩散层中液态水沿程分布的表达式.结果表明:阳极中一般很难有水生成;阴极中加湿度越大,进口压力越大,过量系数越小,液体出现的位置离进口越近,且同一位置液态水的生成速率越大,当阴极气体完全加湿时,液态水的生成速率仅与其到进口的距离、电流密度、膜中水传输系数以及流道的宽度有关,而受流道的高度、过量系数、进口压力以及温度等影响较小.

The distribution expressions of the gas total pressure and water vapor partial pressure along the channel direction were established through analyzing the pressure loss in the channel and diffusion layer. According to the thermodynamics analysis, the expressions of the liquid water generation rate in the anode and cathode were also deduced. The results show that little liquid water can be got in the anode, the liquid water appears closer to the entrance with a larger relative humidity （RH）, higher in- let pressure and less stoichiometry and the water generation rate are also enhanced in the same position in the cathode. Especially, when the reaction gas is completely humid in the cathode, the water gener- ation rate are merely the function of the distance, current, water transport coefficient, and the width of the channel, while the height of the channel, stoichiome^ry, inlet pressure, and temperature have few effect on it.