The effect of fuel gas mixtures and air flow rates on electrical properties of solid oxide fuel cell

Abstract

Fuel Cells are one of the most efficient and environmentally friendly devices for electricity generation, which are developing rapidly and are already in the early stages of commercialization. Solid Oxide Fuel Cells (SOFC) areone of the most promising their types due to the highest efficiency, fuel flexibility (H2, CnHm, CO etc.) and no needs in platinum group catalysts. The performance of SOFC is affected by various polarization losses, which aredependant on selected materials, their structure and SOFC operation parameters. Over the last decade, much attention is given to the study of SOFC’s electrochemical properties at different operating regimes: temperatures, fuels, fuel and oxidantflow rates etc. The work is devoted to studying the influence of the model fuel (5% H2—Ar) and air (oxidant) flow rates on electrical properties of Solid Oxide Fuel Cellat 800 °C to determine the best combination of gas flow rates, which provide the maximum values of specific electric power. The fuel (0,35 l/min) and oxidant (1 l/min)flow rates was found as the optimal operation regime of fuel and air supply for the SOFC tested. The highest electrical densityto be ensured by the model fuel was determined as 34 mW/cm2. The amount / flow rate of oxidant and fuel gases supplied to the fuel cell does not correspond to the ratio of the reagents of the chemical reaction of oxidation of the fuel. This difference is explained by the fact that the SOFC effectiveness of fuel and oxidant utilization depends not only from to the properties structure and materials of each components: anode, cathode, electrolyte, but also from concentration of fuel and oxidant in model fuel or air, which also creates a barrier for oxidant and fuel molecules to reach the reaction zone. Keywords: Solid Oxide Fuel Cell, electrical properties, fuelgasmixtures, hydrogen, oxidant.