Investigating temperature-driven water transport in cathode gas diffusion media of PEMFC with a non-isothermal, two-phase model

Abstract

Temperature distribution affects water transport in the porous medium layer of proton exchange membrane fuel cell (PEMFC) by phase-change-induced (PCI) flow. Thus, it is meaningful to reveal the role of PCI flow in removing water. In the present work, a 1-D, non-isothermal, two-phase model is employed to investigate the water transport in cathode gas diffusion layer (GDL) and micro porous layer (MPL). A dimensionless parameter Ts is also proposed to characterize the relation between PCI flow and capillary-driven (CD) flow. It is found that elevating the operating temperature (from 323.15 K to 363.15 K) can facilitate the PCI flow. The high anode and low cathode relative humidity (RHa90%/RHc50%) case contributes to the optimal output performance, corresponding to the largest Ts number and thermal strain. The thermal strain is insignificant compared with the swelling strain and the hygrothermal strain is influenced by the combination of output performance, water distribution and operating conditions. Furthermore, reducing water saturation (sc) at the GDL/gas channel (GC) interface (from 0.12 to 0.0) is conducive to enhancing the proportion of PCI flow in GDL and MPL. By adjusting the operating temperature, inlet RH and removing water at the GDL/GC interface in time enable enhancement of PCI flow and better performance. This work aims to provide a valuable reference for understanding the water transport process and optimizing water management.