Effect of manufacturing deviations on the thermohydraulic performance of printed circuit heat exchangers with zigzag channels

Abstract

• The etching-induced deformations have subtle effects on thermo-hydraulics; • The bonding-induced deformations is closely related to PCHE thickness; • An estimation model for bonding-induced deformation is proposed and validated; • The semicircular microchannel deformation mechanism is proposed and validated. A printed circuit heat exchanger (PCHE) is an essential component of the supercritical carbon dioxide Brayton cycle ( sCO 2 -BC ), but the effect of manufacturing deviations of PCHEs on thermohydraulic performance is seldom reported. To quantitatively analyse the etching-induced and bonding-induced deformations, 19 test plates/blocks are manufactured for measurement. Numerical simulations are performed to investigate the effects of these geometric deformations. The results indicate that the influences of etching-induced deformations are relatively small, the effect of the channel cross-section shape is more significant than the zigzag angle, and the longitudinal pitch is the weakest contributor. For the oval-shaped channel, the channel width plays a leading role in influencing the heat transfer, while the pressure drop is affected more severely by the channel depth. The channels tend to be narrower and shallower after diffusion bonding, and the bonding-induced channel cross-section deformation can cause large deviations in thermal-hydraulic characteristics, especially for those with thin blocks and few layers. Based on the measurement data, an estimation model for the relative deviation of the channel hydraulic diameter after bonding is proposed for the present manufacturing process.