Effect of polytetrafluoroethylene shedding on water and heat transport in the gas diffusion layer of proton exchange membrane fuel cells

Water and heat management in the gas diffusion layer (GDL) is essential to the performance of proton exchange membrane fuel cells (PEMFCs). The flow and heat transfer model of lattice Boltzmann method (LBM) is used to study the effect of random shedding of polytetrafluoroethylene (PTFE) on water and heat transfer in GDL. The water saturation in the GDL during water invasion, the temperature distribution in the GDL at the stable water distribution, and the remaining water saturation during water removal are analyzed. The results show that different degrees of PTFE shedding lead to different exposure positions of hydrophilic carbon fibers, which may have a positive or negative effect on water transport in GDL. Compared to the case without PTFE shedding, the 20% PTFE shedding increases the water saturation by 0.6%, while the 40% PTFE shedding has a minimum water saturation of 0.438 due to the ability to create multiple water transport paths. PTFE shedding allows for a more uniform temperature distribution within the GDL. However, PTFE shedding hinders water removal, and the 40% PTFE shedding case has the largest remaining water saturation at 0.087 after purging with air.