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

Abstract

The carbon-free energy systems such as nuclear can 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 fulfill these requirements. This work presents the thermal-hydraulic and structural analysis of PCHE for molten salt applications with thermal energy storage. In this study, three distinct 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 has an exponential growth with power generation level with zigzag channel geometry being the highest out of three geometries. Overall, the zigzag channel PCHE is still the most suitable geometry for this application. Zigzag channel geometry should be substituted with an alternative geometry at a high-power application having both airfoil-fin and slotted-fin geometry at relatively identical stress intensity.