Experimental study of turbulent forced convection of nanofluid in channels with cylindrical and spherical hollows

Experimental study of forced turbulent convection of water-based nanofluids with nanoparticles of zirconium oxide (ZrO2) was carried out in smooth tubes and channels with wall heat transfer enhancers. Nanopowders with average particle size of 44 and 105 nm were used in the experiments. The Reynolds number ranged from 3000 to 8000. It is revealed that the increments in the heat transfer coefficient and the pressure drop when using nanofluids depend on the surface shape of the channel. It is shown that nanofluids allow reaching thermal-hydraulic efficiency comparable to that of the channels with artificial heat transfer enhancers. (C) 2017 Elsevier Ltd. All rights reserved.