Mixed-Convection Heat Transfer in Vertical Packed Channels

Abstract

The experimental results of mixed-convection heat transfer in a vertical packed channel with asymmetric heating of opposing walls are reported. The experiments were carried out In the range of 2 < Pe < 2200 and 700 < Ra < 1500. The measured temperature distribution indicates the existence of a secondary convective cell Inside the vertical packed channel in the mixed-convection regime. A correlation equation for Nusselt number in terms of Peclet number Pe and Rayleigh number Ra was obtained from experimental data. A plot of Nu/Pe 1/2 vs Ra/Pe exhibits the transition of heat-transfer results from the natural convection limit to the forced convection limit. The following three convection regimes exist: natural convection regime, 105 < Ra/Pe; mixed-convection regime, 1 < Ra/Pe < 105; and forced convection regime, Ra/Pe < 1