Thermal‐Hydraulic Performance and Entropy Generation Analysis of Turbulent Mixed Convection Chloride Salt Absorber Tube

Abstract Chloride salts are used as the heat transfer (HT) media for the third‐generation concentrated solar power (CSP). Challenges such as localized high‐temperature and uneven wall temperature within the absorber tube (AT) persist. Furthermore, the HT of mixed convection (MC) for molten salt is different from that for common fluid. To address these issues, an AT featuring turbulent MC is proposed and numerically analyzed. Furthermore, the performance of AT is evaluated under various operational parameters. Results indicate that the secondary flow (SF) induced by buoyancy force (BF) generates two vortices, enhancing salt mixing and HT. Consequently, there is a significant improvement in temperature uniformity, accompanied by a substantial reduction in the maximum temperature. Compared to forced convection (FC), the maximum temperature as well as temperature gradient for MC is reduced by up to 242.73 K. Additionally, there is an increase of 3.57–16.76% in the Nusselt number and a 5.98%–30.07% increase in the friction factor. The thermal performance factor (TPF) ranges from 1.016 to 1.070. Moreover, the maximum reduction in the entropy generation rate (EGR) is 16.52%, and the highest enhancement in exergy efficiency (EE) reaches 4.68%. This study provides practical insights for the development of more efficient and secure chloride salt AT.