Fluid flow and heat transfer characteristics in a curved rectangular duct using an Al2O3-water nanofluid

In the present research, the laminar forced convective heat transfer and fluid flow characteristics of an Al2O3-water nanofluid flowing in different pipe bends (i.e., 180° and 90°) have been numerically investigated in a three-dimensional computational domain using the finite volume technique. The effects of different pertinent parameters, such as the Reynolds number of the duct, volume fraction of the nanoparticles, diameter of the nanoparticles, aspect ratio of the duct, and the duct bend angle on the hydrodynamic and thermal characteristics of the flow have been presented. It was observed that heat transfer is augmented by replacing conventional fluid with an Al2O3-water nanofluid. The nanoparticle volume fraction was found to be an important parameter to increase the heat transfer in a pipe bend. It was also observed that the thermo-hydraulic characteristics of the flow changes with the duct aspect ratio, and the heat transfer rate improves with changes in the aspect ratio. The heat transfer in a pipe with a 180° bend was obtained to be higher than in a pipe with a 90° bend at particular values of the volume fraction and Reynolds number. Moreover, the present study computed Nusselt number for a pipe with a 180° bend and a rectangular cross section was validated with the existing literature.