Flow characteristics analysis for multi-path hydrogen supply within proton exchange membrane fuel cell stack

The flow rate distribution of hydrogen between single cells has a significant impact on the performance and durability of the entire proton exchange membrane fuel cell stack, especially for open-cathode stacks. However, few studies consider the effects of fuel distribution on output performance, pressure drop distribution, and temperature distribution simultaneously at the stack level. To investigate the effect of hydrogen distribution on the stack output characteristics, several different multi-path hydrogen supply modes are proposed and explored in this study through the combination of flow network models and experiments. Considering hydrogen reaction consumption in the calculation models. Parameters such as stack voltage, flow uniformity index, dimensionless pressure drop, and temperature uniformity index under different modes are quantitatively compared. The results show that Triple-path hydrogen supply mode has the highest stack voltage of 5.278 V at rated condition, 4% improvement over the lowest Z-shape mode. While Quad-path hydrogen supply mode has the best flow rate distribution and single-cell voltage uniformity, with a maximum voltage difference of only 0.073 V between single cells in the stack. Multi-path hydrogen supply modes provide more uniform pressure drop distribution over the conventional U and Z-shape (with a single path), but the relationship between output performance and the number of hydrogen supply paths is not simply linearly correlated. Furthermore, the whole stack temperature decreases with the increase of hydrogen supply path, but the temperature uniformity is not optimal with the maximum number of paths.