Transient Modeling of Tubular-Designed IIR-SOFC Fueled by Methane, Methanol, and Ethanol

Abstract

It is known that the heating rate during starting-up of Solid Oxide Fuel Cell (SOFC) plays an important role of system performance and lifetime. In the present work, an axial 2-D tubular Indirect Internal Reforming SOFC (IIR-SOFC) model fueled by methane, methanol, and ethanol was developed with the aim of predicting the system temperature gradient during the starting-up period. All predicted results was calculated by using COMSOL^®. The system was also compared with typical SOFC fueled by hydrogen. It was found that hydrogen heating gas required the lowest time to achieve the steady state (around 2 minutes) with the highest heating rate 0.93 K/s, which is not compatible for the thermal stress of SOFC material. The uses of methane, methanol, and ethanol as primary fuel can enhance compatible heating rate with the cell material, from which IIR-SOFC fueled by methanol is the best option in terms of its slow heating rate and high system efficiency. It is noted that the effects of inlet steam/carbon (S/C) ratio and gas flow pattern were also studied. It was observed that changing in S/C ratio is not significantly influence to temperature behaviors of the system. Meanwhile, IIR-SOFC with co-flow pattern provided smoother temperature gradient along cell and higher power density at steady state condition than that with counter-flow pattern.