Parametric study of anodic microstructures to cell performance of planar solid oxide fuel cell using measured porous transport properties

This study reports effects of porosity (ε), permeability (k) and tortuosity (τ) of anodic microstructures to peak power density (PPD) of a single-unit planar anode-supported SOFC based on 3D electrochemical flow models using measured porous transport properties. Applying particle image velocimetry, a transparent porous rib-channel with different ε is applied to measure an effective viscosity (μ_e) in the Brinkman equation commonly used to predict flow properties in porous electrodes. It is found that, contrary to the popular scenario, μ_e is not equal to the fluid viscosity (μ_f), but it is several orders in magnitude smaller than μ_f resulting in more than 10% difference on values of PPD. Numerical analyses show: (1) while keeping k and τ fixed with ε varying from 0.2 to 0.6, the highest PPD occurs at ε = 0.3 where the corresponding triple-phase-boundary length is a maximum; (2) PPD increases slightly with k when k ≤ 10^-11 m² due to the diffusion limitation in anode; and (3) PPD decreases with τ when τ > 1.5 due to the accumulation of non-depleted products. Hence, a combination of ε = 0.3, k = 10^-11 m², and τ = 1.5 is suggested for achieving higher cell performance of planar SOFC.