Thermal characteristics in asymmetrically heated channels fully filled with brass beads

Abstract

This study experimentally investigated the heat transfer characteristics in the asymmetrically heated rectangular channels fully filled with porous materials. Air was used as the coolant. The porous materials were packed by brass beads with average diameters ( d) of 2, 4 and 6 mm. The channel width ( W) was fixed to be 60 mm. Variable parameters were the relative length of packed channel ( L/ d = 5–60), the relative height of packed channel ( H/ d = 1.67–15), and the Reynolds number (Re D = 755–7921 and Re dp = 38–2703). The results indicated that the bead diameter ( d), rather than the hydraulic diameter ( D h), may be a proper parameter to generalize the data for heat transfer in a packed channel. The particle Nusselt number ( Nu ¯ dp ) increased with decreasing L/ d, while the H/ d was not sensitive to Nu ¯ dp . Finally, the correlations of average and local particle Nusselt numbers ( Nu ¯ dp and Nu dp, x ) for various L/ d, H/ d and Re dp were provided.