(i) The nanoparticles increased the heat transfer up to 8% (ii) At the entrance region, the heat transfer enhancement increased and decreased with the increasing axial distance (iii) As the temperature increased, the energy exchange of the nanoparticle-base fluid contact increased
(i) The interface temperature was reduced between the heater and water block (ii) The heat transfer enhanced by the use of the nanoparticles in the base fluid; the maximum heat transfer enhancement was approximately 29% (iii) The increase of the pressure drop was less than the increase in the convective heat transfer
(i) The nanoparticles concentration did not show much effect on heat transfer enhancement in turbulent regime (ii) The ratio of convective heat transfer coefficient of nanofluid to that of pure water decreased with the increasing Reynolds number
(i) Remarkable heat transfer enhancement was observed as well as the pressure drop by the inclusion of the nanoscaled particles into the base fluid (ii) As the tube profile became more flattened, the heat transfer enhancement increased, and the same behaviour was valid for the pressure drop (iii) The maximum heat transfer enhancement was 26.4% at 2% vol. for the flattened tube compared to the pure oil.
: length of the test tube, OD: outer diameter, ID: inner diameter, and Thick: thickness.