Experimental investigation of forced convection heat transfer and friction factor in a tube with Fe3O4 magnetic nanofluid

The nanofluid used was a stable colloidal suspension of magnetite (Fe3O4) nanoparticles of average diameter 36 nm. The convective heat transfer coefficient and friction factor characteristics of Fe3O4 nanofluid for flow in a circular tube is evaluated experimentally in the range of 3000 < Re < 22.000 and the volume concentration range of 0 < phi < 0.6%. Nanofluid heat transfer is higher compared to water and increases with volume concentration. Correlations are developed based on the experimental data useful for the estimation of Nusselt number and friction factor of water and nanofluid for flow in a tube. The heat transfer coefficient is enhanced by 30.96% and friction factor by 10.01% at 0.6% volume concentration compared to flow of water at similar operating conditions. (C) 2011 Elsevier Inc. All rights reserved.