Numerical study of Tesla valve flow field on proton exchange membrane fuel cell performance

Effective flow channels in proton exchange membrane fuel cells (PEMFCs) can provide sufficient reactant and a more uniform reactant distribution, which allows the fuel cells to operate with high performances. The Tesla valve structure is thought to be a feasible structure for channel design due to its one-directional flow characteristics, yielding different performances with different flow directions. Numerical studies were conducted in this work to investigate the impacts of the channel structure, flow direction, and excess air coefficient on the fuel cell performance. Three types of flow channels (straight, symmetric Tesla valve, and asymmetric Tesla valve) and two flow directions (forward and reverse) were studied. The results showed that the maximum power density of the reversed asymmetric Tesla valve increased by 10.08 % compared to that of the conventional straight channel. Detailed research revealed that the Tesla valve resulted in a more intense flow than the conventional straight channel. The symmetric Tesla valve resulted in a greater pressure drop than the asymmetric valve. The Tesla valves with reverse flow could significantly limit the formation of an oxygen dead zone. Hence, enhanced Zdirection mass transfer and the lowest standard deviations of the oxygen and water distributions were observed. The effects of the excess air coefficient on the net power density were also studied. Increasing the excess air mass to the cathode facilitated the enhancement of the electrode voltage but required more parasitic power due to the growth in the pressure drop along the flow channel.