Two-phase flow in GDL and reactant channels of a proton exchange membrane fuel cell

•Review of two-phase flow in gas diffusion layer and reactant channels of PEMFCs.•Droplet–reactant channel wall interaction with/without air flow.•Water coverage on the GDL–reactant channel interface by liquid water.•Oxygen transport resistance at the gas diffusion layer–reactant channel interface.•Two-phase flow pressure drop model for PEMFC reactant channels.

Understanding the effect of two-phase flow in the components of proton exchange membrane fuel cells (PEMFCs) is crucial to water management and subsequently to their performance. The local water saturation in the gas diffusion layer (GDL) and reactant channels influences the hydration of the membrane which has a direct effect on the PEMFC performance. Mass transport resistance includes contributions from both the GDL and reactant channels, as well as the interface between the aforementioned components. Droplet–channel wall interaction, water area coverage ratio on the GDL, oxygen transport resistance at the GDL–channel interface, and two-phase pressure drop in the channels are interlinked. This study explores each factor individually and presents a comprehensive perspective on our current understanding of the two-phase transport characteristics in the PEMFC reactant channels.