Resolving the conflict between water retention and cooling enhancement in air-cooled PEMFCs through an adjustable-cathode-outlet (ACO) technique

In common air-cooled proton exchange membrane fuel cells (PEMFCs), cathode channels simultaneously perform cooling and air delivery functions, which leads to conflicts between water retention and cooling enhancement. To solve this problem, an adjustable cathode outlet (ACO) technique was presented. The ACO technique incorporates an open rib (OR) configuration and a movable baffle at the cathode outlet. This technique reduces the air velocity within the cathode channel and directed more airflow through the opened rib, and thereby simultaneously achieves cooling requirement and water retention improvement. The average membrane temperature with ACO design reduced by 5.0 K at an output voltage of 0.6 V, and the power density increased by 2.95% at a load current density of 1.18 A/cm² comparing to the common PEMFC design. A larger baffle height leads to a better water retention ability. Under an environment of 40.0 °C and 10.0% relative humidity, the structure with baffle height of 1.1 mm obtained an average membrane water content at 15.0, which is 5.0 more than that of the common structure. The oxygen transfer was not affected with the ACO structure and the pressure drop through the air path could be maintained in an acceptable level with an appropriate baffle height.