Owing to the great potential in converting various gaseous fuels to electricity at very high electrical efficiency, solid oxide fuel cells (SOFCs) could be an important building block for a green and efficient future energy system. However, since SOFCs are essentially made from thin layers of different ceramic materials and ceramic-metal-compounds, they are sensitive to high spatial and temporal temperature gradients which can especially occur during transient operation, for example start-up and electrical load variation processes of a SOFC system. The transient effects can even be more pronounced when additional chemical effects influence the cell temperature, such as internal reforming and water gas shift reactions resulting from utilization of hydrocarbon-based fuels like natural gas or biosyngas. In this work, we thus investigate the mechanism of the start–up and electrical load variation processes of a SOFC stack based on a reduced CFD stripe model through transient simulation. Using a fuel composition with high methane concentration, the effect of internal reforming on the cell temperature distribution during the start-up is found to be very pronounced, leading to strong temperature changes especially at the fuel inlet. Notably, reasonable operating temperature is found effective to avoid cracks at anode support layer and extend the lifetime of the SOFC. Overall, it is found that critical situations for the cells might occur, and further study is necessary to find methods for mitigation of the strong temperature gradients.     «

Owing to the great potential in converting various gaseous fuels to electricity at very high electrical efficiency, solid oxide fuel cells (SOFCs) could be an important building block for a green and efficient future energy system. However, since SOFCs are essentially made from thin layers of different ceramic materials and ceramic-metal-compounds, they are sensitive to high spatial and temporal temperature gradients which can especially occur during transient operation, for example start-u...     »