Cell integrated multi-junction thermocouple array for Solid Oxide Fuel Cell temperature sensing: N+1 architecture

Understanding the cell temperature distribution of Solid Oxide Fuel Cells (SOFC) stacks during normal operation has multifaceted advantages in performance and degradation studies. Present efforts on measuring temperature from operating SOFC stacks measure only gas channel temperature and do not reveal the cell level temperature distribution, which is more important for understanding cell’s performance and its temperature-related degradation study. Authors propose a cell integrated multi-junction thermocouple array for in-situ cell surface temperature monitoring from an operating SOFC. The proposed thermocouple array requires far fewer numbers of thermo-elements than thermocouples would require for the same number of temperature sensing points. Hence, it causes far less disturbance to the cells’ performance during sensing. The array was sputter deposited on the cathode of a commercial SOFC using alumel (Ni:Al:Mn:Si – 95:2:2:1 by wt.) and chromel( Ni:Cr – 90:10 by wt.) as thermo-element materials. The thermocouple array was tested in a furnace covering the entire operating temperature range of a typical SOFC. Each sensing point of the array could measure temperature independently, and as accurately as a thermocouple. Thus, the concept of multi-junction thermocouples is experimentally validated and its stability on a porous SOFC cathode is confirmed.