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

In the present research, the laminar forced convective heat transfer and fluid flow characteristics for Al2O3-water nanofluid flowing in different bend (i.e., 180o and 90o) pipes have been investigated numerically 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 nanoparticle, the diameter of the nanoparticle, aspect ratio of the duct and the duct bend angle on the hydrodynamic and thermal characteristics of the flow has been presented. It is observed that the heat transfer is augmented by replacing conventional fluid by Al2O3-water nanofluid. The nanoparticle volume fraction is found to be an important parameter to increase the heat transfer in the bend pipe. It is also observed that the thermo-hydraulic characteristics of the flow changes with the duct aspect ratio, and the heat transfer rate is improved with aspect ratio. The heat transfer with a 180o bend pipe is obtained to be higher than a 90o bend pipe at a particular value of volume fraction and Reynolds number. Moreover, the present computed Nusselt number for 180o bend pipe of rectangular cross-section has been validated with the existing literature. validated with the existing literature.