Anomalous Transport of Thermal Disturbance in a Planar SOFC Stack

A fast parallel model of coupled heat and current transport in a planar solid oxide fuel cell (SOFC) stack is developed. The model is used to simulate the thermal effect of a resistive spot in a 15-cell stack. The small circular spot cools off the cell by 1 K in the region of nearly the same radius (cold spot). Unexpectedly, this cold spot "propagates" along the stack axis with only a minor loss in the spot amplitude. The perturbation analysis of the governing equations shows that in typical conditions, the amplitude of the cold spot decays exponentially with the distance along the stack axis. However, the characteristic scale of the exponent appears to be large. The theoretical value of this scale (14 cells) agrees well with the value obtained from the numerical calculations (12.5 cells). The analysis also reveals that at large current densities or in stacks of the large transversal size, the temperature disturbance oscillates along the stack axis. The physics of these effects are discussed.