Viscosity and Friction Factor of Aluminum Oxide–Water Nanofluid Flow in Circular Tubes

Abstract

Experiments have been conducted to characterize the viscosity and friction factor of aluminum oxide (Al2O3) nanoparticle dispersions at 6 vol. % in water. Rheological characterization of the Al2O3 nanofluid has shown that it exhibits a Newtonian fluid behavior for the shear rate range of 6 to 122 s−1 at temperatures between 6 and 75 °C. Friction factor results of the nanofluid flowing through circular tubes of 1 m in length with different inner tube diameters (2.97 and 4.45 mm) were experimentally measured in the laminar and the onset of transition regions. The experimental results from this study indicate that, when the nanofluid properties are properly characterized, the friction factors of the Al2O3 nanofluid are largely in agreement with classical friction factor theory for single-phase flow. An early transition to turbulent flow is observed for the nanofluid flow at a Reynolds number of approximately 1500, when compared with water flow where transition occurs at the textbook Reynolds number of roughly 2300.