Experimental investigation on convective heat transfer and hydrodynamic characteristics of magnetite nanofluid under the influence of an alternating magnetic field

An experimental study has been carried out on the laminar forced convective heat transfer of Fe3O4/ water nanofluid (ferrofluid) under an external magnetic field. Here, the ferrofluid flows into a long uniformly heated parallel plate channel and is influenced by an external magnetic field generated by four electromagnets. The efficient arrangement of the electromagnets is obtained by numerical simulations and primary experiments. Effects of magnetic field intensity and frequency on the convective heat transfer and pressure drop have been investigated at different concentrations (1, 1.5, and 2 Vol%) and flow rates (200 <= Re <= 1200). It is observed that the convective heat transfer has a direct relation with the Reynolds number and ferrofluid concentration. Moreover, at a constant Reynolds number, the magnetic field intensity increases the heat transfer. Note that there exists an optimum frequency for every single Reynolds number which increases by Reynolds number. Our results also show a maximum heat transfer enhancement of 16.4% by the use of ferrofluid, in the absence of a magnetic field. This value is increased up to 24.9% and 37.3% by application of constant and alternating magnetic field, respectively. (C) 2015 Elsevier Masson SAS. All rights reserved.