Variations in buoyancy-aided turbulent mixed convective heat transfer along a vertical rectangular channel

Abstract

We performed buoyancy-aided turbulent mixed convection experiments using a vertical rectangular channel heated on one side. To achieve high buoyancy, mass transfer experiments were performed by analogy with heat transfer using a copper electroplating system. Piecewise electrodes were used to measure local mass transfer coefficients along the channel. The Grashof number ranged from 8.05 × 104 to 1.01 × 1010, and the Reynolds number from 985 to 25,450. Local turbulent forced convection correlation was developed based on the correlations of Petukhov et al. and Gnelinski. The local mass transfer rates of mixed convective flow exhibited both impairments and enhancements compared to the rates of pure forced convection, attributable to the effects of buoyancy. Heat transfer of turbulent mixed convection was increasingly impaired with the height of the heated section increased. The Particle image velocimetry (PIV) confirmed the distorted velocity profiles and the redistributed turbulent shear stress.