Temperature and Current Density distributions in a 100 cm2 PEM Fuel Cell: Effects of flow field designs
G.M. Cabello González, Baltasar Toharias, Felipe Rosa, José Guerra, Alfredo Iranzo
Abstract
Electro-thermal mapping provides valuable insights into the performance evaluation of polymer electrolyte membrane fuel cells (PEMFCs) by depicting the spatial distribution of current density and temperature. In this study, electro-thermal maps were generated for three different designs of 100 cm 2 PEMFC flow fields (conventional serpentine with two different channel depths, and serpentine-tapered). The performance of each design was characterized by analyzing the surface (in-plane) distributions of current density and temperature at different cell voltages. At elevated current densities, a linear increase in the non-uniformity of temperature and current density distribution is observed. The central region of the bipolar plate exhibits higher temperatures, whereas the region with high current densities is situated near the hydrogen inlet, gradually diminishing as the hydrogen depletes towards the outlet. Results show that , in general, the tapered flow field design exhibits better performance with a more homogeneous temperature and current distribution throughout the entire active area. This behavior can be attributed to better water management and gas diffusion towards the electrode due to the acceleration and pressure increase of the reactant fuel gas along the narrowing channel. Novel insights were identified by applying the Current Distribution Mapping (CDM) technique for analyzing current density and temperature in-plane distributions under dynamic load conditions, comparing the different channel depths or tapered designs during the dynamic operation of the cell. During dynamic tests, temperature increased rapidly for increasing loads but the decrease was more slowly when load was lowered, leading to an overall gradual temperature rise and less homogeneous distribution at higher currents, while the current distribution adjusted almost instantly with constant standard deviation during both load increases and decreases.