质子交换膜燃料电池的三维数值模拟

Three-Dimensional Numerical Simulation of Polymer Electrolyte Membrane Fuel Cells

对一种质子交换膜燃料电池进行了整个单电池的三维数值模拟．计算中采用单相等温模型，数值求解用整场离散、整场求解的方法，同时采用已知电流通过Butler—Volmer方程修正过电位获得电池电压的方法模拟电化学动力学过程．数值结果与实验值的对比表明，所采用的单电池计算模型在大部分工况下获得的输出电压与实验值偏差均可控制在10％～20％以内．计算并分析了单电池局部电流密度分布，同时将单电池模型与典型单元模型的计算结果进行了对比，发现两者在电流密度、质量组分的分布上均存在明显的差异，其原因主要在于典型单元边界条件设置所致．该工作将有助于对质子交换膜燃料电池的流动、传质与电化学过程进行进一步的数值研究．

A numerical three-dimensional prediction of a full cell （entire-cell） of a kind of polymer electrolyte membrane fuel cells （PEMFCs） was conducted by developing an in-house code. The isothermal single-phase model was adopted and the governing equations were discretized and solved in full fields. Moreover, the electrical current density was specified, and the output volt- age of entire-cell was obtained by updating the over potential. The local current density distribution was also obtained by solving the Butler-Volmer equation, and its average value was then compared with the pre-specified one. The simulation results are in agreement with the experimental data. It is found that the local volumetric current density is in order of 1.0 × 10^8 A/m^3. Simulation was also conducted for a typical unit of the cell under the same operation condition. The resuits show the significant difference between the entire-cell simulation and the simulation of a typical computational unit （TCU） in the local distribution of current density and mass fraction. This might mainly result from the assumptions of uniform channel inlet and fully developed chan- nel outlet in TCU. The present work confirms the importance to conduct the three-dimensional computation of entire PEMFCs.