A numerical scheme for the effect of flow-field orientation on water management in PEM fuel cell is developed. Since there are limitations on the location of proton exchange membrane fuel cell such as portable applications, different configurations are used for proper water management. Therefore, the best configuration must be chosen for the most efficient and stable operation of the fuel cells. In this research, a 3D numerical model is proposed based on the VOF method in order to simulate the effects of gravity on the gas–liquid two-phase flow in a full-scale single-serpentine flow-field. This model, which is validated by the experimental results, considers the microstructure of the gas diffusion layer by two square pores in every cross section along the channels. The simulations are done for the vertical and horizontal fuel cells. The effects of water coverage ratios and flow regimes on pressure drop and the resulting parasitic power loss are investigated for different configurations. In the vertical orientation, the channels are placed horizontally or vertically in each configuration. The results reveal that in the vertical cells, when the channels are located horizontally and the inlet manifold is embedded on the upper side of the flow-field, the pressure drop is the lowest. The reason is that the film flow is formed in the channels and the gravity assists in the water removal. However, when both the cell and channels are vertical and the cathode inlet manifold is placed on the bottom of the flow-field, the pressure drop and the resulting parasitic power is the highest. This is due to the gravity is against the water purging from the elbows leading to formation of long plugs along the channels. The present numerical model can be used for simulation of two-phase flow in channels of the serpentine flow-field at any cell orientation angle by changing the gravity direction in the model.

建立了流场方向对PEM燃料电池水管理影响的数值方案。由于质子交换膜燃料电池（例如便携式应用）的位置受到限制，因此使用不同的配置进行适当的水管理。因此，必须选择最佳配置以使燃料电池最有效和稳定地运行。在这项研究中，基于VOF方法，提出了一个3D数值模型，以模拟重力对全尺寸单蛇形流场中气液两相流的影响。通过实验结果验证了该模型，该模型通过沿通道的每个横截面中的两个方孔来考虑气体扩散层的微观结构。对垂直和水平燃料电池进行了仿真。对于不同的配置，研究了水覆盖率和流动方式对压降的影响以及由此产生的寄生功率损耗。在垂直方向上，在每种配置中，通道都水平或垂直放置。结果表明，在垂直单元中，当通道水平放置且进气歧管嵌入流场的上侧时，压降最低。原因是在通道中形成了膜流，并且重力有助于水的去除。但是，当电池和通道都垂直且阴极入口歧管放置在流场的底部时，压降和产生的寄生功率最高。这是由于重力与从肘部排出的水相反，导致沿通道形成了长堵塞。通过改变模型中的重力方向，本数值模型可用于模拟在任何单元取向角下的蛇形流场通道中的两相流动。