Effects of Geometry and Material Properties on the Residual Stress of Glass-to-metal Seals in Solar Receiver Tubes

AbstractThe solar receiver tube is a key component to convert the solar energy into thermal energy in parabolic trough solar power system. The residual stresses which are generated during the cooling process of glass-to-metal sealing significantly influence the reliability of receiver tube. In order to lower the seal failure probability, the effects of geometry and material properties of glass- to-metal seals on the residual stress are analyzed using finite element method in this paper. The effects of the material properties of stainless steel 304, stainless steel 430, Kovar on the sealing residual stress can be presented. Although each of these different sealing material combinations can have enough sealing strength, the glass-to-metal seals with larger tensile stresses can cause the failure of the receiver tube. Moreover, effects of geometry of the metal tube and the glass tube on the residual stress are also analyzed. The stress distributions in the glass side analyzed by the finite element method (FEM) were in agreement with the ones calculated by analytic solution (AS) approach. The X-ray measurement results also proved the validation of the FEM. The dangerous tensile stresses mainly occur at the glass-metal interface. The results of this study have important implications on the optimization of seal configuration in the solar receiver tubes