Abstract
Metal foam flow field (MFFF) is a promising approach to improve the proton exchange membrane (PEM) fuel cell performance by enhancing mass transfer. However, the widely considered uniform MFFFs exhibit noticeable weak flow at the corners of the MFFF, where challenges arise in reaction gas transport and water drainage in large-area MFFFs. In this study, MFFF with non-uniform pore sizes is proposed to improve the performance of large-area PEM fuel cells. The impact of different cathode flow fields on the performance and internal transport characteristics are studied experimentally. The results show that adopting the MFFF with diagonally decreased pore size along the flow direction from inlet to outlet shows the best performance, which is 111.4% higher than the parallel serpentine flow field and 14% and 10.6% higher than the uniform MFFF with pore size of 35 and 75 ppi, respectively. The improvement is found to be the combined effects of enhanced reactant transport and improved water management especially in downstream of the cell. In addition, by analyzing the effects of operating conditions, it is revealed that the non-uniform pore size design of MFFFs is an excellent alternative to a uniform MFFF under various extreme operating conditions like high humidity and low stoichiometry. This study provides a new strategy for the design and improvement of MFFFs for large-area fuel cell stacks.
Published Version
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