Hydrothermal assessment of ferrofluids in a metal foam tube under low-frequency magnetic field

In this research, an experimental study is conducted on the hydrothermal characteristics of Fe3O4/water ferrofluid flow through a metal foam tube under constant and alternating low-frequency magnetic field. The Nusselt number and friction factor of Fe3O4/water ferrofluids are measured and presented at different nanoparticle concentrations, Reynolds numbers, magnetic field intensities as well as frequencies. The results have shown that when the magnetic field intensity and frequency increase, there will be an enhancement in the Nusselt number. A maximum of 36.2% improvement in the Nusselt number of ferrofluid is obtained at Re = 200, for 2% nanoparticle weight fraction under alternating magnetic field with 20 Hz frequency. Also, the friction factor of Fe3O4/water ferrofluid is observed to be higher than that of DI-water. Moreover, the effect of alternating low-frequency magnetic field is found to be insignificant on the friction factor at the constant magnetic field. The thermal performance index of 1.26 is achieved by applying alternating magnetic field intensity of 400 G with 20 Hz frequency at Re = 1000 for the ferrofluid with 2% weight fraction. Finally, a polynomial neural network based on the group method of data handling (GMDH) is established to predict the Nusselt number and friction factor in this study. It is obtained that GMDH-type neural network provides a useful model which can precisely estimate those parameters.