Metal foam flow field in polymer electrolyte fuel cells: Numerical and experimental evaluation

This paper presents a comprehensive evaluation of metal foam flow field application within polymer electrolyte fuel cells (PEFCs) and compares it with conventional serpentine channels from both computational fluid dynamics simulation and experimental viewpoints. The experiments are designed to investigate the effects of material, area density, compression ratio, and final thickness of metal foam. Additionally, the influence of housing plate material and relative humidity (RH) is tested here. The results reveal that at RH = 75%-100%, the best flow field design is nickel foam with a compression ratio of 70%, a final thickness of 0.5 mm, and an SS-304 housing plate, which delivers a great limiting current density. In comparison with the serpentine channel case, the PEFC with this foam flow field shows a 10% improvement in maximum power density (901 vs 989 mW cm⁻²) and a 45% improvement in limiting current density (2140 vs 3110 mA cm⁻²). While at RH = 30%, the same foam flow field with a final thickness of 1 mm is a superior option. The experiments also indicate that maximum power density increases by 23% (from 684 to 841 mW cm⁻²) as the compression ratio rises from 0% to 70% while reducing final thickness from 1 to 0.5 mm causes a 5.8% enhancement in (from 935 to 989 mW cm⁻²) cell performance. Simulation results reveal that metal foam is more effective in evenly distributing reactants, resulting in an average oxygen mass fraction at the cathode catalyst layer that is 38% higher than the serpentine channel case.