Measurement of Solid Oxide Fuel Cell at High Temperature
Researchers at the University of South Carolina continue important research into the mechanics of new fuel cell technologies. Solid Oxide Fuel Cells (SOFCs) can be designed in either a planar or non-planar configuration. Since modern fuel cell assemblies are constructed from several different materials and operate at relatively high temperatures, 550℃~750℃, the experimental characterization of the in-situ response is of interest for model validation. This study employs stereo-vision and stereo-DIC from Correlated Solutions to measure both full-field surface strains and the out-of-plane displacement on the surface of a heterogeneous cell during operation.
To obtain in-situ images of fuel cell materials, several technical issues were successfully addressed to perform stereo-imaging of a fuel cell at elevated temperatures. These included (a) modifications of the lens system to develop a far-field microscope arrangement, acquiring images of a small region imaging with a large stand-off; (b) application of a speckle pattern capable of withstanding elevated temperatures; (c) construction of the fuel cell to allow imaging through an open hole of the furnace; (d) development of a camera support system to ensure stability for both calibration and experiment imaging and (e) ensuring continuous air circulation around the furnace and camera-lens system.
Since full field deformation is obtained using the measurement method, viewing the spatial variations in a strain that occurs during heating is necessary to identify conditions that induce localization in the deformations, including increases in out-of-plane motion in specific regions of the fuel cell at selected temperatures. The strain measurements are also used to determine the average thermal coefficients of expansion. Taken together, the measurements provide baseline data to assist material developers and fuel cell manufacturers.
Figure 1
Average of each surface strains εxx, εyy and εxy over the entire specimen surface.
Figure 4
Confidence coefficient for images at 593℃.
Figure 2
Out of plane displacement, w(x,y), at three temperatures. All units in mm.
Figure 3
Strain fields εxx(x,y) and εxy(x,y) at 761℃.
Data courtesy of Ning Li, NanSheng Xu, Michael Sutton and Kevin Huang
Department of Mechanical Engineering, University of South Carolina