Experimental investigation on heat transfer and hydrodynamic behavior of magnetite nanofluid flow in a channel with recognition of the best models for transport properties

Laminar forced convective heat transfer and pressure drop of water based magnetite (Fe3O4) nanofluid in a uniformly heated parallel plate channel are studied experimentally. The local convective coefficients are measured at both thermally developing and fully developed regions in the Reynolds number range of 200-1200. Transport properties measurement experiments are also conducted. The thermal conductivity and viscosity of the Nanofluid are measured at three different volume fractions, φ = 1%, 1.5% and 2%, in the temperature range of 20-60 °C and are used to develop appropriate correlations. The accuracy of the proposed thermal conductivity correlation in predicting the convective heat transfer coefficients is compared with that of the different existing models. Results show that the Brownian motion has a significant effect on the thermal conductivity of the nanofluid. It is also indicated that using the current correlations lead to the closest results to the experimental data. Furthermore, the convective heat transfer experiments show that using magnetite nanofluid increases the convective heat transfer up to a maximum of 16% at Re = 1200 and φ = 2% compared to the DI-water. However, increase of the pressure drop is an inevitable consequence of using nanofluids. Thus, the optimum operating condition is obtained based on the maximum heat transfer enhancement per pressure loss.