Effect of Different Tube Structures on Heat Transfer of Supercritical CO2 in Serpentine Micro-Tubes

In order to understand the effect of different tube structures on the heat transfer characteristics of supercritical CO₂ in heating serpentine micro-tubes, five structures are investigated. At the same inlet Reynolds number, because the periodic disturbance frequency of boundary layer and centrifugal force decrease with the increase of curvature radius and the boundary layer thickens with the increase of tube diameter, the comprehensive heat transfer performance of serpentine micro-tubes decreases with the increase of curvature radius and tube diameter. Gravitational buoyancy is independent of curvature radius but increases with the increase of tube diameter. Centrifugal force and centrifugal buoyancy decrease with the increase of curvature radius and tube diameter.