Laminar convection heat transfer and flow performance of Al2O3-water nanofluids in a multichannel-flat aluminum tube

The heat transfer experiments of Al2O3-water nanofluids were carried out at fixed Reynold number and velocity in a multichannel-flat aluminum tube. The studies we have performed revealed that the convection heat transfer coefficient increased about 5.9% at 0.5 vol.% Al2O3 concentration at Re = 1732. While at a constant velocity, higher addition of nanoparticles had no evident influence on the heat transfer performance. Compared with theoretical correlations, the data obtained were accorded with Shah equation (deviation <10%) except for those in the entrance. Then a comparative study of Al2O3-water nanofluids and the base fluid was made on the local heat transfer coefficient. The results indicated a higher heat transfer augmentation (11.1%) in the entrance region for 0.5 vol.% Al2O3-DW nanofluid, which seems to have a bearing on the thermal conductivity enhancement and the thermal boundary layer thickness reduction. The friction factor and the pressure drop were also studied and the results revealed that the pressure drop slightly increased with the volume concentration of nanoparticles. For 0.5 vol.% Al2O3-DW, the average pressure drop increased about 4.4%. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.