EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER AND PRESSURE DROP CHARACTERISTICS OF FERROFLUIDS IN THE PRESENCE OF MAGNETIC FIELD AND LAMINAR FLOW CONDITIONS

Abstract

In this study, the heat transfer performance with forced convection of two different water-based nanofluids was investigated by applying an alternating magnetic field in a minichannel. CoFe₂O₄-water and MnFe₂O₄-water nanofluids have been prepared at 0.5 vol.% and tested. The tests were carried out in a minichannel under laminar flow conditions in the Reynolds numbers range of 300-1700. Nusselt numbers of each fluid used in the experiments were calculated and compared. At the Reynolds number of 1500, the CoFe₂O₄-water nanofluid exhibited an increase of 12% compared to pure water, while the MnFe₂O₄-water nanofluid showed an increase of 4%. The Nusselt number increased in both nanofluids by applying the magnetic field to nanofluids. The highest Nusselt number obtained was 9.35 for the CoFe₂O₄-water nanofluid in the presence of magnetic field. While this increase was more pronounced at low Reynolds numbers, a lower rate of increase was obtained at high Reynolds numbers. In addition, the use of nanofluids significantly increased the pressure drop compared to the base fluid. While an almost 100% increase in the pressure drop was observed for the CoFe₂O₄-water nanofluid compared to pure water, the 65% increase for the MnFe₂O₄-water nanofluid was maximum. At the highest Reynolds numbers, the maximum pressure drops were determined as 3.4 kPa for the CoFe₂O₄-water nanofluid and 3 kPa for the MnFe₂O₄-water nanofluid. It was also detected that the friction factor for CoFe₂O₄-water and MnFe₂O₄-water nanofluids was 80% and 40% higher, respectively, than for the base fluid.