Coupling Lattice-Boltzmann and Finite Volume CFD Methods for Efficient Co-Simulation of Two-Phase Flow in the Porous Transport Layers of PEM Water Electrolyzers

Abstract

Polymer electrolyte membrane water electrolysis (PEMWE) can be modeled using computational fluid dynamics (CFD) for research and development purposes. Continua that contain multiple phases or represent porous media are typically treated as homogeneous regions with bulk-average properties. Per this assumption, the finite volume method (FVM) can be employed to solve such problems with simple geometries. This is computationally inexpensive, and it can be utilized to assist the design of macroscopic cell components such as flow fields. However, this method is limited in its ability to link porous transport layer (PTL) morphology to local phase composition and cell performance.The Lattice-Boltzmann method (LBM) has demonstrated the ability to accurately simulate two-phase flow in detailed porous media for fuel cells1,2. Being a particle-based CFD method enables it to resolve the liquid/gas interphase within the pores of replica PTL samples at higher computing speed than other methods. Figure 1 shows an example of oxygen evolution inside the Ti powder PTL sample for a PEMWE device at an average current density of 2 A/cm2. This outcome can aid in the development of porous media for both fuel cell and electrolysis applications3.We always strive to build the simplest possible models that fully describe a system at the length scale of interest. Macroscale FVM simulations can be used to aid the investigation of porous media properties and morphology by providing a realistic current distribution. Meanwhile, experimentally validated LBM simulations produce output data that are useful for modeling two-phase flow in a homogeneous region using the FVM. Satjaritanun, S. Hirano, I. V. Zenyuk, J. W. Weidner, N. Tippayawong, and S. Shimpalee, J. Electrochem. Soc., 167, 013516 (2019).Satjaritanun, S. Hirano, A. D. Shum, I. V. Zenyuk, A. Z. Weber, J. W. Weidner, and S. Shimpalee, J. Electrochem. Soc., 165, F1115 (2018).Satjaritanun, M. O'Brien, D. Kulkarni, S. Shimpalee, C. Capuano, K. E. Ayers, N. Danilovic, D. Y. Parkinson, and I. V. Zenyuk, iScience, 12, 101783 (2020). Figure 1