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 (epsilon), permeability (k) and tortuosity (tau) 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 epsilon is applied to measure an effective viscosity (mu(e)) in the Brinkman equation commonly used to predict flow properties in porous electrodes. It is found that, contrary to the popular scenario, mu(e) is not equal to the fluid viscosity (mu(f)), but it is several orders in magnitude smaller than mu(f) resulting in more than 10% difference on values of PPD. Numerical analyses show: (1) while keeping k and tau fixed with epsilon varying from 0.2 to 0.6, the highest PPD occurs at epsilon=0.3 where the corresponding triple-phase-boundary length is a maximum; (2) PPD increases slightly with k when k <= 10(-11) m(2) due to the diffusion limitation in anode; and (3) PPD decreases with tau when tau > 1.5 due to the accumulation of non-depleted products. Hence, a combination of epsilon=0.3, k = 10(-11) m(2), and tau = 1.5 is suggested for achieving higher cell performance of planar SOFC. (C) 2009 Elsevier B.V. All rights reserved.