Effect of Porous Microstructural Properties on the Results of a Cell-Level Model in Solid Oxide Fuel Cells

Abstract

A detailed micro-model framework is used for calculating effective microstructural properties for the porous anode and cathode electrodes in solid oxide fuel cells (SOFCs). The resulting microstructural parameters obtained from this detailed numerical approach are then applied to a macro-scale SOFC cell model. The performance of the SOFC cell model is determined by the geometric and effective transport microstructural properties which properly accounting for representative porous SOFC electrode structures.

Development of a SOFC Performance Model to Analyze the Powder to Power Performance of Electrode Microstructures

“…A particle-based construction model ( 7), (13) was employed to generate synthetic electrode microstructures. The technique attempts to replicate a wet ceramic manufacturing process and generates electrode structures comprised of overlapping spherical particles.…”

“…Sintering of these structures is commonly simulated by allowing the particles to overlap each other and form porous transport networks. Various groups have studied detailed electrode microstructures to evaluate the TPB length (1),( 7), (8), multiphase transport coefficients (12)(13)(14), and phase percolation (10), (15), (16) and relate these properties to electrode performance. Digitized electrodes allow for the actual microstructure of different manufacturing techniques to be examined and experimental testing of the electrode to occur before digitization, whereas synthetic electrodes allow for in-depth analysis of ensembles of representative microstructures to be undertaken, facilitating parametric studies.…”

Computational Fluid Dynamics Modeling of Solid Oxide Electrolysis Cell

“…The universal gas constant is given as ܴ = 8.3124 (J•K -1 •mol -1 ), the effective gas diffusivity of species is represented by ‫ܦ‬ eff (m 2 •s -1 ), the molecular weight of species is given as M i (kg•kmol -1 ), as well as the molar and mass fractions of gas species are denoted by X i and Y i , respectively. The source terms in Equations [1][2][3][4] are given as follows:…”

“…The effective gas diffusivity of species ‫ܦ(‬ eff ) in Equation [3] is reduced relative to diffusion in a free gas by a factor of the porosity (߳) and the tortuosity factor (߬) as follows:…”

“…Although the backbone of the computational model is based on the OpenFOAM solvers, the required modules were functionalized as a coupled electrochemical model and were developed and integrated on top of the OpenFOAM framework. OpenFOAM based CFD models have been developed to model the behavior in solid oxide fuel cells (2,3). Hence, the computational model in this study builds on the previous OpenFOAM based CFD models (2,3), which were originally developed for the SOFCs.…”