An integrated experimental and numerical investigation of performance and heat-mass transport dynamics in air-cooled PEMFCs with a bamboo-shaped flow field design

The convoluted heat and mass coupling transfer phenomena and uneven physical field distribution in air-cooled proton exchange membrane fuel cells (PEMFCs) critically affect their power density and water-thermal management. As a crucial component, the cathode flow field is vital for fuel management, heat dissipation, and water transport of air-cooled PEMFC. Refining the flow field design is a key strategy to approach the above challenges. In this study, an innovative bamboo-shaped flow field is proposed and experimentally verified in a 25 cm2 single cell, which proves its effectiveness in boosting the heat-mass transfer capacity and power density of air-cooled PEMFC. Also, it reduces fuel supply energy costs. Meanwhile, a three-dimensional multiphase numerical model is applied to explore the coupled transfer mechanisms and distribution features of liquid water, reactant, and heat under this design. Experimental results show that, at a high load of 0.65 A cm−2, the novel design increases pumping power by 17.8 % compared to the conventional parallel flow field. Despite this, it accomplishes a 5.45 % enhancement in power density and a 4.17 % rise in energy efficiency. Besides, it exhibited superior cooling efficiency and effectively mitigated localized hot spots within the cell. Numerical analysis shows that the segmental acceleration effect and the vortex regions within the bamboo-shaped design are the key factors to improve cell performance. It alleviates the issues of dehydration of the porous electrode and decreased mass transfer capability caused by high airflow velocity gradients. Further, the high heat transfer entropy region caused by the bamboo joint structure elevates the heat dissipation in porous electrodes. Simultaneously, the design also boosts the reactant distribution uniformity in the porous electrode.