The Effect of Flow Channel Geometry on Thermomechanical Performance of Printed Circuit Heat Exchanger (PCHE)

Abstract

Abstract Climate change has garnered attention of communities world-wide. The carbon-free thermal energy systems such as nuclear benefit from compact and highly efficient heat exchanger technologies. The plate-type compact heat exchangers such as the Printed Circuit Heat Exchanger (PCHE) holds promise to fulfil these requirements. The chemical etching and diffusion bonding technology expands PCHE application for several different nuclear technologies. This work presents the thermal-hydraulic and structural analysis of PCHE for molten salt application with thermal energy storage. In this study, three different types of geometry are chosen for the analysis i.e., the zigzag channel type, the airfoil fin type, and the slotted fin type. For the working fluid, FLiBe (Li2BeF4) and Solar Salt (60% NaNO3 and 40% KNO3) are chosen for hot side and cold side respectively. Titanium grade 5 is chosen as the structural material. The study is conducted by Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) analysis. The thermomechanical behavior including pressure drop, fluid temperature, velocity profile, stress, and deformation of the flow channel were considered in this work. From the results, the zigzag channel geometry gives the best thermal hydraulic performance in terms of heat transfer and pressure drop. The structural analysis shows that the stress intensity of all three geometries can exceed the maximum allowable stress (MAS) under certain conditions. Overall, the zigzag channel PCHE is still the most suitable geometry for this application.