Improvement of thermal and water management of air-cooled polymer electrolyte membrane fuel cells by adding porous media into the cathode gas channel

In air-cooled polymer electrolyte membrane fuel cells (PEMFCs), the contradiction between cooling and water retention renders the improvement of cell performance really challenging. In the present study, cathode flow field is designed by inserting porous media into the gas channel to properly distribute flow rate between gas channel and cooling channel. A three dimensional two-phase non-isothermal model of PEMFCs is adopted to investigate the reactive transport processes in air-cooled PEMFCs. The results show that by inserting porous media into the outlet of the gas channel, the current density can be improved by 18.2% compared with the conventional parallel flow field. Then, effects of permeability of the porous media and the cathode outlet set-point temperature on the performance of PEMFC are examined, which both show a nonmonotonic influence on fuel cell performance. The reason can be attributed to the complex trade-off between cooling, water retention and reactant supply. Finally, effects of the altitude are explored, and it is found that the proposed novel design also shows advantage in alleviating the performance reduction due to the increase of altitude. The proposed design is proved to be a promising scheme to alleviate the contradiction between cooling and water retention in air-cooled PEMFCs.