Determination of temperature distribution of a solid oxide cell stack using regenerated fiber Bragg gratings

The temperature distributions inside the solid oxide cell (SOC) stacks are conventionally monitored using thermocouples. Despite their reliability, employing a large number of thermocouples is often not practical due to their electrical conductivity and significant cabling effort. In this work, an optical fiber with an array of seven regenerated fiber Bragg grating (RFBG) sensors was integrated into a modified Jülich F10 solid oxide cell stack to address these challenges. The transient temperature profiles during heat-up and current–voltage characterization, as well as the steady state profiles during fuel cell operation under varying conditions were recorded using both the RFBG sensors and nine type-N thermocouples. The RFBG sensors provided accurate, localized temperature measurement up to 800 °C in the stack. Based on the recorded temperature profiles, the underlying causes for thermal gradient and heat dissipation of this five-layer SOC stack were analyzed and stack operating strategies were discussed. This study demonstrated the feasibility and advantages of using RFBG sensors in SOC applications and established previously inaccessible boundary conditions for stack level simulation work. • RFBG sensors conduct multipoint temperature measurement in a SOC stack. • Asynchronous heating of the stack caused thermal gradient during heat up. • RFBG sensors are more suitable for capturing transient temperature changes. • Significant temperature change during IV curve leads to incorrect estimation of ASR. • Heat conduction dominates the heat dissipation during fuel cell operation.