Forced convection of the brass-beads packed bed situated in a vertical oncoming flow

Abstract

This study experimentally investigated the convective heat transfer and pressure drop of a vertical oncoming airflow onto the brass-beads packed bed. The 120 mm-length ( L) brass-beads packed bed was fully filled in a horizontal rectangular channel having a cross section of 60 mm width ( W) and variable height ( H). The flow entry, with variable width ( w j ), was located at the center of the upper wall of the test channel. Besides, three kinds of packed beds with various bead diameters ( d) were used herein. The ranges of relevant parameters were w j / L = 0.212–1, H/ L = 0.083–0.25 and d = 2–6 mm. Experimental results reveal that, at w j / L = 0.212, the local Nusselt number ( Nu) at the stagnation point ( x/ L = 0) right under the flow entry was maximal and then monotonically decreased along the transverse flow direction. However, when w j / L = 0.583 and 1, the Nu firstly decreased from x/ L = 0 to x/ L = 0.1, then rose along the transverse flow direction. Additionally, under the same pumping power, the largest average Nusselt number ( N u ¯ ) appeared on w j / L = 0.212, H/ L = 0.083 and d = 6 mm, and the smallest N u ¯ happened at w j / L = 1, H/ L = 0.25 and d = 2 mm. The largest N u ¯ was around 3 times of the smallest N u ¯ . This work systemically completed the parametric studies on heat transfer and pressure drop. The relevant correlations of experimental results were also presented.