Mass transfer characteristics of the catalyst layer in proton exchange membrane fuel cells during hot air convection drying

Hot air convection drying is the predominant technique for industrial fabrication of the catalyst layer (CL) in proton exchange membrane fuel cells (PEMFCs). This study established a CL hot air convection drying experimental setup modeled on an actual production line to measure drying curves. The CL was dried by hot air convection drying at 30-90 degrees C, 0.5-2 m/s. Three thin film drying models (Wang and Singh model, Midilli model, and Dincer and Dost model) were used to describe the drying kinetics of CL. The results showed that the Dincer and Dost model best fit the drying kinetics of CL with an average relative deviation of less than 12.4 %. The analytical approach developed by Dincer and Dost was first used to determine the effective moisture diffusion coefficient (Deff) and the convective mass transfer coefficient (hm) in the CL drying process, verifying its applicability. The results showed that under the current experimental conditions, Deff ranged from 1.97 x 10-9 to 5.86 x 10-9 m2/s, primarily influenced by air temperature, while hm varied from 4.29 x 10-6 to 6.69 x 10-6 m/s, mainly influenced by air velocity.