Mathematical Model of Carbon Corrosion in a Direct Carbon Fuel Cell

摘要

The Direct Carbon Fuel Cell (DCFC) is a type of fuel cell using carbon as fuel and molten carbonate as electrolyte. Although the primary anodic reaction is believed to be a 4-electron carbon oxidation reaction, to explain the performance of the DCFC in practice it is necessary to consider the 2-electron CO oxidation reaction as well as the reverse Boudouard reaction. Taking these multiple reactions into account, this work develops a 1-D macrohomogeneous model, and investigates the current and concentration distribution in the DCFC anode. The result shows that the active zone is mostly located on the portion of the anode bed nearest the electrolyte matrix, and that the active zone of a 4-cm high anode bed occupies only 30% of the total height. On the upper portion, the overall reaction rate is nearly zero since the overall anodic reaction, composed of two compensating electrochemical reactions, is exactly equal to Boudouard reaction. Therefore, the overall carbon corrosion within the region is contributed not only by chemically driven Boudouard reaction but also by electrochemically driven Boudouard reaction.