High temperature strength and inelastic behavior of plate–fin structures for HTGR

In this paper, both high temperature strength and inelastic behavior of plate–fin structures were discussed for applying these structures to the compact heat exchangers such as recuperative and intermediate heat exchangers for high-temperature gas-cooled reactors (HTGR). Firstly tensile, creep and fatigue tests of the brazed plate–fin model of small size were carried out to obtain the rupture strength and inelastic behavior. The influence of the braze filler metal thickness on the tensile strength was experimentally studied and a possibility of predicting both the tensile and creep strength was discussed using the data of base material of plates and fins. Secondly, we demonstrated the fabrication of large-size core with a dimension of 1000 mm, and also demonstrated that the bonding ratio in this core was improved up to almost 100% by adopting the pressurized tank system in the brazing process. Finally, we proposed the stress analysis method of plate–fin structures on the basis of the equivalent-homogeneous-solid concept, and carried out the elastic–plastic analysis of recuperative heat exchanger for HTGR. Characteristics of stress–strain behavior were discussed together with a possibility of predicting the fatigue life of the structure.