Effect of gas flow rates and Boudouard reactions on the performance of Ni/YSZ anode supported solid oxide fuel cells with solid carbon fuels

• Published in: Journal of power sources Vol. 196; no. 10; pp. 4719 - 4723
• Main Authors: Chien, Andrew C., Chuang, Steven S.C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.05.2011; Elsevier
• Subjects: Anode effect; Applied sciences; Boudouard reaction; Carbon; Carbon monoxide; Coconut coke; Density; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Flow rate; Fuel cells; Fuels; Nickel; Oxidation of solid carbon; Pulse transient studies; Solid oxide fuel cells; Yttria stabilized zirconia; Boudouard reaction; Oxidation of solid carbon; Coconut coke; Pulse transient studies; Solid oxide fuel cells; Performance evaluation; Coke; Stabilized zirconia; Carbon; Solid oxide fuel cell; Cermet; Gas flow; Anode support; Nickel; Oxidation
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2011.01.033

[Display omitted] ► Lower carrier gas flow rates enhanced the cell performance of carbon-based solid oxide fuel cells (C-SOFCs) by increasing the extent of electrochemical oxidation of CO due to the long residence time of CO. ► The power generation from C-SOFCs can be further increased by increasing gasification rate of solid carbon via Boudouard reaction. ► CO and CO2 can displace adsorbed hydrogen on the solid carbon fuels of C-SOFCs. The effects of carrier gas flow rates and Boudouard reaction on the performance of Ni/YSZ anode-supported solid oxide fuel cells (SOFCs) have been studied with coconut coke fuels at 800°C. Decreasing flow rates of carrier gas from 1000 to 50mlmin−1 increased open circuit voltages and current densities from 0.71 to 0.87V and from 0.12 to 0.34Acm−2, respectively. The increased cell performance was attributed to the increasing extent of electrochemical oxidation of CO, a product of Boudouard reaction. The contribution of CO oxidation to current generation was estimated to 66% in flowing inert carrier gas at 50mlmin−1. The pulse transient studies confirmed the effect of flow rates on cell performance and also revealed that CO and CO2 can displace adsorbed hydrogen on carbon fuels. Flowing CO2 over coconut coke fuel produced CO via Boudouard reaction. The presence of CO led to a highest power density of 95mWcm−2, followed by a concurrent decline of power density and CO concentration. The declined power density along with decreasing CO concentration further verified contribution of gaseous CO to the power generation of C-SOFC; the decreasing CO concentration showed a typical kinetics behavior of Boudouard reaction, suggesting the loss of active sites on carbon surface for the reaction.