Numerical and experimental investigations on internal humidifying designs for proton exchange membrane fuel cell stack

For an automotive proton exchange membrane fuel cell engine, the efficient water content management is critical to its overall efficiency and lifetime. The fuel cell stack designed with internal humidifying effect is a promising solution for enhanced performance and compact system integration. In this work, a novel internal humidifying fuel cell stack design is proposed which utilizes the water and heat transfer through membrane in the triangular gas feed areas. Validated by the experimental test, a coupled three-dimensional model is developed to compare the fuel cell performance with three different feed area functions. The active feed area design performs the worst with the lowest reaction uniformity, while the humidifying feed area design presents the best performance with greatly improved water content distributions. The internal humidifying stack design is suitable for operations under dry reactants inflow conditions with more performance improvement and more evenly distributed reaction, which is beneficial for the compact fuel cell system integration without external humidifiers. To further improve the internal humidification effects of the stack, the asymmetric inlet/outlet feed areas with specific flow channels will be studied in future work.