These slides were presented at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

The higher-than-ever need to decarbonize energy intensive sectors and to increase their efficiency is motivating a shift from carbon-rich fossil fuels used in low-efficiency combustion devices (e.g. engines, turbines) to non-carbon fuels (e.g., hydrogen) electrochemically converted in high-efficiency fuel cells systems. The fuel cells technology extends the decarbonization possibilities of battery-based systems to generate power where the energy requirement is presently higher than the limited energy density of batteries, e.g. heavy-duty transportation or medium-range aviation. Multi-dimensional simulation techniques as Computational Fluid Dynamics (CFD) is one of the main ways costs can be lowered by decreasing reliance on physical prototypes and resources those require, shifting the development pathway to digital prototypes. In this context, the industrial development of fuel cells systems has focused on the Polymeric Electrolyte Membrane Fuel Cell (PEMFC) type, due to its higher power density, low-temperature operation, fast response time, inherent modularity, and absence of corrosive liquid electrolyte with respect to other fuel cell types. The key for an optimal PEMFC operation is to obtain a high and uniform thermal-hydration state of the electrolytic membrane during its operation, necessary for the maximization of the rate-limiting ionic conductivity. Hence the water transport through the porous media (Gas Diffusion Layers and Catalyst Layers, GDL and CL, respectively) is not only crucial to optimize the cell'™s operation, but also highly complex to model in view of the multi-phase nature of the fluid and of the ubiquitous presence of solid walls and small pores. In this study, two Eulerian multi-phase models are implemented in Simcenter STAR-CCM+ and compared in the unique framework of PEMFCs, namely the mixture multi-phase (M2) and the two-fluid (TF) model. A reference case from literature is simulated to compare both multi-phase models, critically discussing the impact of the hypotheses of both models on the cell operation, as well as those of a Eulerian modelling approach in this context. The results provide guidelines for the modelling of multi-phase water transport in PEMFC porous media, contributing to the advancement of the simulation techniques for the power generation and propulsion industries.