| Fuel cells represent a promising energy alternative to the traditional combustion of fossil fuels. In particular, solid oxide fuel cells (SOFCs) have been of interest due to their high energy densities and potential for stationary power applications. One of the key obstacles precluding the maturation and commercialization of planar SOFCs has been the absence of a robust sealant. A leakage computational model has been developed and refined in conjunction with leakage experiments and material characterization tests at Oak Ridge National Laboratory to predict leakage in a single interface metal-metal compressive seal assembly as well as multi-interface mica compressive seal assemblies.; The computational model consists of three submodels: a macroscopic model, a microscopic model, and a mixed lubrication model. The macroscopic model is a finite element representation of a preloaded compressive seal interface, which is used to ascertain macroscopic stresses and deformations. The micro scale contact mechanics model accounts for the role of surface roughness in determining the mean interfacial gap at each discretized node within the sealing interface. An averaged Reynolds equation derived from mixed lubrication theory is applied to approximate the leakage flow across the rough, annular interface. The composite model is applied as a predictive tool for assessing how certain parameters (i.e., temperature, applied compressive stress, surface finish, and elastic thermo physical properties) affect seal leakage rates. |
