Effect of channel length on interdigitated flow-field PEMFC performance: A computational and experimental study

• Flow within interdigitated flow-field design PEM fuel cells was modeled using COMSOL.
• Increasing channel length leads to maldistribution of channel pressure and cross flow.
• A cell that could operate with different lengths and flow fields was built and tested.
• Short interdigitated flow field shows higher performance due to more even cross flow.

This study examines the effect of increased channel length on the distribution of flow gases and cell performance in an interdigitated flow-field PEMFC. A numerical model was used to simulate the pressure distribution and gas flow in 5 cm and 25 cm channel length interdigitated flow fields that have eight channels with fixed channel and land widths of 1 mm. The results show the distribution of flow under land areas (cross flow) is subject to maldistribution in the longer cell while the shorter cell produces relatively homogenous cross flow along its length. An experimental test cell was designed to run with the same channel lengths, under similar conditions to those modeled. Inlet pressure data was recorded to account for parasitic pump losses, used to calculate net system power curves. Results show that a shorter channel interdigitated flow field may produce both higher maximum power and limiting current densities compared with longer cells.