Leakage Studies With Seals for Solid-Oxide Fuel Cells

This research seeks to characterize the gas leakage of a mica-based compressive seal assembly in planar solid-oxide fuel cells through modeling and experiment. In particular, it is of interest to assess how certain physical parameters (i.e., seal material composition, compressive applied stress, and surface finish) affect leakage rates. Finite element analysis is used to determine the macroscopic stresses and deformations in the sealing interface, while a microscale contact mechanics analysis is employed to model the role of surface roughness on the mean interfacial gap at the interface. An averaged Reynolds equation from mixed lubrication theory is applied to model the leakage flow across the sealed interface, which is of nanometer to micrometer dimensions in the vertical direction. In conjunction with the mathematical modeling, leakage results are reported. For these tests, an annular Inconel tube was pressed against a stainless steel substrate, creating an annular sealing zone. The inside of the tube is pressurized with a test gas, the mass of which is monitored during the leakage experiment. Test results are compared to model predictions.