Vortex-driven heat transfer enhancement in supercritical CO2: Structural optimization with claw-shaped lattice design for enhanced thermal performance

Abstract

This study conducted computational simulations to comparatively investigate the effects of various typical claw-shaped lattice structure arrays (LSAs) on the flow and heat transfer performance of supercritical CO₂ in a vertically upward heated tube. The results indicate that the LSAs could effectively mitigate heat transfer deterioration (HTD) of supercritical CO₂, by regulating the coupling mechanism between buoyancy and flow acceleration effects, reducing wall temperature, and enhancing heat transfer coefficient. Furthermore, the influence of buoyancy and flow acceleration on heat transfer characteristics are systematically analyzed, revealing the advantages of claw-shaped lattice structures in suppressing HTD. The findings demonstrate that the four-claw LSA exhibits the most significant heat transfer enhancement, as its complex lattice geometry could induce stronger and more intricate vortex system, thereby facilitating momentum exchange and energy transport between the near-wall and core flow regions. Additionally, the four-claw LSA exhibits excellent robustness in heat transfer performance across varying structural parameters. Moreover, a generalized heat transfer prediction model applicable to both claw-shaped LSA tubes and smooth tubes is established. The proposed model accurately captures over 99 % of the simulation data, with a prediction error within ±5 %, aiming at providing crucial theoretical support and engineering guidance for optimizing supercritical CO₂ heating systems.