Modeling and analysis of internal water transfer behavior of PEM fuel cell of large surface area

The PEM fuel cell has been widely used in the area of transportation and power station. The surface area of a fuel cell is enlarged to provide high enough power but the problem of analysis of internal water content behavior follows tightly. Many scholars have investigated the mathematical models of a small fuel cell and validated them through experiment. Besides, the introduction of AC impedance technique helps find relationship between water content and membrane resistance. Based on their research, an approach is put forward in this paper to model and analyze the internal water content behavior in a fuel cell of large surface area. For large surface area, three special cases are studied according to the actual operating states at cathode outlet. The first case applies to a fuel cell with no saturated water vapor at both outlets while in the second and third case, the fuel cell is divided into an electrochemical reaction zone and no reaction zone owing to emerging liquid water. The indicators of model are the water content profile inside membrane and the total membrane resistance. The simulation results show that the net water transfer coefficient has significant influence on the performance of the membrane and the constituents of anode side are easy to be varied. In addition, when the fuel cell is operated in counter-flow mode with emerging liquid water, the only back diffusion of water from cathode to anode helps improve the state of the membrane.