Effects of gas diffusion layer thickness on PEM fuel cells with composite foam-rib flow fields

TL;DR

This study uses 3D simulations to analyze how GDL thickness affects PEM fuel cell performance, revealing optimal configurations for different flow field designs and water management.

Contribution

It provides new insights into how cathode and anode GDL thicknesses influence cell efficiency and water management in CFRFF and CRFF designs.

Findings

Thinner cathode GDL improves performance in CFRFF design.

Optimal cathode GDL thickness exists for CRFF design.

Reducing anode GDL thickness increases water content and decreases Ohmic loss.

Abstract

Gas diffusion layers (GDLs) play a crucial role for the performance of proton exchange membrane fuel cells (PEMFCs). The utilization of composite foam-rib flow fields (CFRFFs) can alter the reactant gas transfer pattern, hence improving the efficiency of under-rib reactant gas transfer and water drainage. The impact of the cathode and anode GDL thicknesses (h_{c,GDL} and h_{a,GDL}) on the performance of CFRFF design is investigated by three-dimensional multiphase non-isothermal numerical simulation in this study. The results indicate that for the conventional rib flow field (CRFF) design, there is an optimal h_{c,GDL} for optimal cell performance, while for the CFRFF design, as h_{c,GDL} becomes thinner, the cell performance increases, and the trend is dominated by the variation of the oxygen concentration. Under a thin GDL, the rib width of the CRFF design should be as small as possible to minimize concentration polarization loss, while the rib width of the CFRFF design can be slightly larger. Furthermore, by decreasing the thickness of h_{a,GDL} in both the CRFF and CFRFF designs, there is an increase in the dissolved water content in the ionomer of the cathode CL and a subsequent decrease in the Ohmic polarization loss.