Numerical investigation of thermal-hydraulic design of a printed circuit steam generator

Abstract

Steam generator is the biggest component of SMR. Therefore, reducing the size of the steam generator will ultimately affect the overall size of the module. Printed Circuit Heat Exchanger (PCHE) is a compact type of heat exchanger that offers a promising prospect for replacing conventional U-tube heat exchangers. Due to its high heat transfer surface area to volume ratio and its capability in high-pressure applications, PCHE can be used as steam generators in SMRs. This study investigates the possibility of using PCHE heat exchanger as a steam generator using Computational Fluid Dynamics (CFD). CFD study was performed on a reduced numerical model consisting a of single unit cell of the PCHE block keeping in view of the periodic structure of the geometry. CFD model was validated against the results of Haratyk et al. Thermal hydraulic performance of zigzag channel geometry was also analyzed for various bend angles ranging from 15°, 25°, 35°, and 45° for mass fluxes ranging from 1000 kg/m2s to 2250 kg/m2s. The friction factor, Nusselt Number and performance factor are calculated for various mass flow rates. Nusselt Number increases with bend angle and mass flux, whereas the friction factor decreases with mass flux and increases with bend angle. A maximum value of 1.45 for the performance factor was attained for a bend angle of 35° in comparison to the straight channel. The performance factor was improved further to 1.5 by introducing a short straight section having a length of 5 mm at each zigzag bend with a bend angle of 35°.