Numerical study on gas-liquid transport uniformity in full-scale flow field of proton exchange membrane fuel cells

Distribution zone governs airflow transmission and distribution within large-scale flow field, which further affects the discharge of liquid water produced. This paper combines experimental validation and computational fluid dynamics (CFD) methods to elevate mass transfer coherence in full-scale flow field (375 cm2). For the first time, circulation number λ and drainage maldistribution (DM) are introduced to quantify variations in water and gas transport homogeneity attributable to the distribution zone. Effect on orientation and spacing of dot matrix, as well as main field structure are investigated. The results reveal that full-scale flow field inlet and outlet distribution zones manage the behavior of gas and liquid transport. Specifically, dot matrix flow field with an inclination angle α = 90° demonstrates superior flow uniformity, while α = 45° exhibits the fastest initial drainage rate. Optimal comprehensive mass transfer and drainage consistency are achieved with a vertical dot matrix spacing of S = 1.2 mm ∼ 1.5 mm, yielding the lowest maldistribution factor (MF) and DM number of 0.15 and 0.04 respectively. This configuration results in a maximum improvement of 58.4 % and 43.1 %. Notably, a novel aspect is that the drainage rate in full-scale flow field follows an exponential distribution, with peak efficiency factor R = 0.29 observed at α = 90°and S = 1.5 mm.