PNNL

Abstract

In this paper, numerical modeling was used to understand of the effect of the geometry and mechanical properties of various components in SOFCs on the level and distribution of stresses in the stack during operating and cooling. The results of these modeling analyses will help stack designers reduce high stresses in the seals of the stack so that structural failures are prevented and high stack mechanical reliability is achieved to meet technical targets. In general, it was found that the load carrying capacity of the cathode contact layer was advantageous for reducing the transmitted loads on the cell perimeter seal under operating environments of SOFCs, but the amount of reduction depends upon the relative stiffness values of the cell, interconnect, porous media, and support structures. Comparison of a fully bonded interface to a frictionless sliding interface resulted in 30-50% less transmitted load through the perimeter seal, with the greater reductions due to stiffer contact/media/interconnect structures. These results demonstrate that the mechanical contribution of the contact layer can be substantial and warrant design consideration