Investigating control of convective heat transfer and flow resistance of Fe3O4/deionized water nanofluid in magnetic field in laminar flow.

This paper studies the convective heat transfer and flow resistance of Fe3O4/deionized water nanofluids in laminar flow under the control of an external magnetic field. The basic thermophysical parameters including viscosity, specific heat capacity and thermal conductivity are investigated to describe the fundamental performance of heat transfer and flow resistance. In the absence of the magnetic field, the heat transfer coefficients and flow friction could not change significantly at nanoparticle volume concentration of 0.05%. In the presence of the magnetic field, it can enhance heat transfer and flow resistance by 6% and 3.5% when the magnets interlace on both sides of the tube. The dynamic magnetic experiments discussed the heat transfer increase process in detail. The heat transfer and the flow resistance increase by 11.7% and 5.4% when magnetic field strength is 600 Gs, nanoparticle volume concentration is 2% and Reynolds number is 2000. The radial shuttle movement of magnetic nanoparticles in the cross-section, micro convection in base fluid and the slip velocity between the nanoparticles and the base fluid are considered the main reasons for heat transfer enhancement.