Convective heat transfer and friction factor of aqueous Fe3O4 nanofluid flow under laminar regime

In present study, the effect of magnetic field on heat transfer enhancement and friction factor of Fe3O4/water nanofluid is experimentally investigated. For this purpose, well-dispersed nanofluids with concentrations of 0.1 and 0.2 % (by mass) in presence of stabilizer are synthesized. Then the experiments are conducted at different Reynolds numbers and magnetic field strengths in an apparatus containing a horizontal circular tube with a length of 1000 mm and diameter of 7 mm. According to the obtained results, the Nusselt number improves with an increase in Reynolds number and concentration of nanopowders. The same result is observed with increasing the magnetic field strength. Moreover, the friction factor of nanofluids is more than that of pure water due to the presence of solid nanoparticles. According to the obtained results, the magnetic field does not impose a significant increase in the amount of friction factor. Considering heat transfer enhancement and friction factor together with a parameter named performance index, it is revealed that privilege of using ferrofluids (improving heat transfer) far outweighs their demerit (increasing friction factor) and the ferrofluids investigated in this paper are capable to be utilized in practical applications.