Effect of liquid water in flow channel on proton exchange membrane fuel cell: Focusing on flow pattern

Abstract

The liquid water in channel is a critical factor affecting the oxygen transport and fuel cell performance. However, the research considering the real gas–liquid interface is insufficient and the effect of flow pattern on mass transfer is still not clear. In this research, the volume of fluid model is added into the fuel cell model to track the two-phase flow in cathode channel (CCH) and a two-dimensional multi-phase fuel cell model is established and validated. The result shows that the liquid water in CCH could change the gas flow path by forming the variable cross-section gas channel. Then it changes the oxygen concentration and distribution, and finally affects the fuel cells performance. The flow pattern is founded to be the critical factor affecting the performance. The initial film flow leads to the long-time large-area water coverage on the cathode gas diffusion layer surface, and the serious local oxygen starvation and current density degradation. When the water content is 10.0%, the average and minimum current density decreases by 4.23% and 7.49% respectively. Besides, the initial slug flow has server deformation and fragmentation, which leads to the output performance fluctuation. Besides, the initial droplet flow has small effect on the performance, and even strengthen the performance by enhancing the local oxygen transportation. Based on this research, regulating the flow pattern is the key means to improve the influence of two-phase flow on fuel cell performance.