Methodology for PEMFC CFD Simulation Including the Effect of Porous Parts Compression

Abstract

In this paper, a three-dimensional, multi-physics and multi-phase CFD model is presented and validated on straight single-channel configurations to analyse the influence of the channel/rib width ratio. In the first part, two cases with wide/narrow channel/rib spacing are reproduced from a literature campaign including neutron radiography (NRG) measured water distribution, which is well reproduced in simulations thanks to the novel implementation of an in-house developed macro-homogeneous catalyst layer sub-model. In the second part, the inclusion of an adapted compression model from literature allows to investigate in detail the effect that the deformation of the porous parts (diffusion media and catalyst layers) has on the cell performance, considering two levels of compression (i.e. clamping pressure). All transport properties (flow/energy/charge) are locally modified as a function of the inhomogeneous compression acted by the BPPs, e.g. influencing flow permeability and thermo/electrical conductivity. The obtained numerical results are compared against those from the undeformed geometry, highlighting a relevant operational difference and explaining it as a compression-related oxygen starvation. The study presents a comprehensive model for PEMFC simulation, including an efficient catalyst layer model and demonstrating the relevance of including the often-neglected compression effect on full-scale cell (or stack) models.