Effects of Cooling Process of Al2O3-water Nanofluid on Convective Heat Transfer

Research has been done to investigate the convective heat transfer and pressure drop of nanofluid, using alumina-water nanofluid under laminar flow regime. The test section was using 1.1 m long and 5 mm inner diameter tube of a double-pipe heat exchanger with constant wall temperatures. The hot nanofluid is flowing inside tube, while the cold water flows outside. The volume concentration of the nanoparticles varied from 0.15%, 0.25% and 0.5%. Experiment shows that the convection heat transfer increases remarkably with the increase of the nanoparticles concentration under various values of Reynolds number. The Nusselt number increases about 40.5% compared to pure water under 0.5% volume concentration. The pressure drop of nanofluid increases slightly with increasing volume concentration. However, compared with using pure water the difference of the pressure drop is insignificant, so that the use of nanofluid has little penalty on pressure drop.