Comparison of predicted and measured mixed convection heat transfer from an array of discrete sources in a horizontal rectangular channel

Abstract

Experiments and supporting three-dimensional computations have been performed to investigate mixed convection heat transfer from a four-row, in-line array of 12, square heat sources which are flush mounted to the lower wall of a horizontal, rectangular channel. The experimental data encompass heat transfer regimes characterized by pure natural convection, mixed convection, laminar forced convection, and the initiation of transition to turbulence. The variation of the row-average Nusselt number with Reynolds number exhibits a minimum, suggesting that, due to buoyancy-induced flow, heat transfer may be enhanced and pumping power requirements reduced by reducing the flow rate. Appropriate scaling parameters are introduced to characterize the strength of the buoyancy-induced secondary flow and to delineate conditions for which it is significant.