Enhanced Mass-Transport Study of Fuel-Cell Gas Diffusion Layer under Nonuniform Assembly Force

Abstract

This study investigates the impact of nonuniform assembly forces on the mass transfer characteristics of the proton exchange membrane fuel cell. Initially, utilizing a solid mechanics model, the influence of assembly forces on gas diffusion layer (GDL) material properties, including porosity, permeability, and diffusion coefficients, is explored. Under a 2 MPa assembly force, the strain distribution in the GDL exhibits a symmetric structure, with maximum strain occurring below the rib, reaching 66 μm. This indicates that assembly forces alter the GDL structure, affecting mass transfer characteristics. Comparing material properties under varying assembly forces reveals that, with increasing strain, porosity and permeability gradually decrease while diffusion coefficients increase. This variation positively impacts activation and concentration polarization, particularly enhancing the removal of liquid water. Additionally, the study investigates the effects of different forms of nonuniform assembly forces, such as incremental and decremental forces. Experimental validation confirms the optimization effects of a 2–1.5 MPa decremental assembly force on fuel-cell performance, including enhanced mass transfer rates and reduced ohmic and concentration polarization. This research provides novel insights for fuel-cell design, aiming to improve mass transfer characteristics and overall performance.