Numerical Analysis of Thermal Deformation and Residual Stress for the Brazed Plate-Fin Structure

Abstract

Compared to traditional shell-and-tube exchangers with the same material, compact plate-fin heat exchangers (PFHE) made of brazed stainless steel have superior heat transfer capability, less volume, lighter weight and low cost. Therefore it has been widely used in many industries, such as air separation, petrochemical, aerospace, energy etc. and PFHE has been the typical candidate to realize the miniaturization of heat exchanging equipments, which are the enabling technology for the miniaturization of chemical and thermal systems. It is negligible that residual stresses and thermal distortion under the effect of thermal cycle, self-constraint and clamping pressure load during brazing for the brazed plate-fin structure that has the millimeter-level function cell. This paper presents a thermo-mechanical finite element analysis for determining the deformation and residual stress of multi-layers stainless steel AISI 304 plate-fin structure, which are counter-flow and brazed with amorphous nickel-base filler metal BNi-2, based on the actual brazing process. The feature of deformation and residual stresses distribution are reported and the effect of 3 factors including the number of layers, brazing temperature, clamping pressure loads on the residual stresses and the distortion are investigated respectively.