Pulsating TiO2/water nanofluids flow and heat transfer in the spirally coiled tubes with different magnetic field directions

Abstract

In this study, four different heat transfer enhancement techniques (Pulsating flow, nanofluids, curved tube, and magnetic field effect) are combined to enhance heat transfer in this study. In experiment, eight permanent magnetic bars are arranged with three different magnetic field directions. Effect of pulsating flow frequency, magnetic fields directions on the convective heat transfer characteristics and friction factor of TiO2 nanofluids in the spirally coiled tubes are considered. Due to the thermal boundary disruption and high mixing of nanofluids, the heat transfer rate is promoted. The pulsating frequency and magnetic field have significant effect on the heat transfer enhancement. The Nusselt number from the pulsating flow is higher than that from the continuous flow whereas the magnetic and pulsating flow has slightly increment of the friction factor. © 2017 Elsevier Ltd