Methanol and Ethanol Fuels in Solid Oxide Fuel Cells: A Thermal Imaging Study of Carbon Deposition

摘要

Near-infrared (N1R) thermal imaging is used to study anodes of anode-supported solid oxide fuel cells (SOFCs) when operating with alcohol fuels. Relative propensities for carbon formation can be determined from surface cooling under fuel flows and subsequent heating under oxidizing conditions at temperatures between 700 and 800 ℃. Ethanol forms considerable amounts of carbon at all temperatures and voltages studied as evidenced by substantial cooling related to carbon reactions and heating under oxidizing conditions. Methanol operation depends greatly on cell temperature and voltage. At 700 ℃, temperature changes resemble those with ethanol, suggesting carbon deposition is occurring. At 800 ℃, there is less cooling, which indicates that the oxide flux at higher polarizations mitigates the effects of endothermic carbon reactions. Under oxidizing conditions after fuel exposure, the small observed temperature increase demonstrates that little carbon is formed. At 750 ℃ the cooling depends on voltage, revealing a set of conditions where cooling from endothermic reactions and heating from exothermic reactions are balanced. The results show that while dry ethanol is not a clean fuel under any of our conditions, methanol can be at higher temperatures. N1R thermal imaging proves a valuable stand-off technique for identifying cell deterioration in situ, with potential for process monitoring in operating SOFCs.