Measurements of natural convective heat transfer of the inclined torus

Abstract

Experiments were conducted to investigate the natural convective heat transfer characteristics of an inclined torus. The Rayleigh numbers ranged from 4.54 × 106 to 1.23 × 108 and the inclination angle was varied from 0° to 80° Mass transfer experiments were performed based on the analogy between heat and mass transfer using the CuSO4H2SO4 copper electroplating system. The heat transfer of the inclined torus exhibited a trend similar to that of an inclined cylinder, with a gradual decrease in heat transfer with the inclination angle due to the variation of vertical cross-sectional shape. However, the inclined torus demonstrated better heat transfer performance than an inclined cylinder as the curved structure interrupts the formation of the stable boundary layer underneath the torus. The flows were visualized by Particle Image Velocimetry (PIV) and the heat transfers, by the electric plating patterns. New correlations were proposed to predict the heat transfer coefficient of the inclined torus as a function of Rayleigh number, inclination angle, and toroidal ratio.