Heat Transfer Model for Mixed Convection of Supercritical Carbon Dioxide in Horizontal Channels

Abstract

When a material crosses its critical point or a pseudocritical temperature at which the specific heat of the material at a constant pressure is maximal, the thermal and hydraulic properties vary significantly. Due to the density variation, flow acceleration and buoyancy occur and result in abnormal heat transfer characteristics. Particularly, the buoyancy influences a shear stress distribution near the wall for vertical flow and causes a secondary flow at a cross-section for horizontal flow. An experimental study was carried out in order to investigate the heat transfer characteristics for the horizontal flow. Based on the analyses, a mixed convection heat transfer model was proposed to involve a natural convection by the secondary flow. The proposed model was based on the thermal resistance theory in a turbulent boundary layer. It was evaluated using experimental data of other studies as well as this study. It was found that the proposed model showed an improved.