Exergy-based pore-network optimization of gas diffusion layers for enhanced efficiency in proton exchange membrane fuel cells

This work introduces a new exergy-based pore-network optimization framework of thermodynamic engineering Gas Diffusion Layers (GDLs) in Proton Exchange Membrane Fuel Cells (PEMFCs). In contrast to the traditional continuum or fully transport-based models, the proposed methodology will combine stochastic pore-network modelling with local entropy generation mapping and multi-objective optimization with the use of the NSGA-II to directly minimize the exergy destruction and to maximize the electrochemical performance. Mass diffusion, viscous dissipation, heat transfer, and electrochemical reactions irreversibility’s are solved at the pore scale, which allows spatial localization of thermodynamic hotspots. Findings show that optimal microstructures, which minimize the destruction of exergy by 18–24%, increase peak exergy efficiency by about 11%, and increase current density at 0.6 V by almost 68%. Entropy generation through diffusion was found to be the most important irreversibility mechanism, contributing over 45% of total exergy loss at high-load operation, and thus topology control of pores is indeed very important. Multi-dimensional response surfaces provided a narrow optimal design window at porosity in the range of 0.63–0.72 and tortuosity in the range of 1.5–1.9 at which the penalties associated with transport or structure dominate. The combined thermodynamic-microstructural optimization guarantees a direct quantitative connection between pore level topology and second-law performance, which offers a fresh design paradigm of high-efficiency and durability-improved PEMFC infrastructures.