Author : Snehal V. Kadbhane and Dilip R. Pangavhane

Convective heat transfer of water based ferrofluid flowing through a pipe was analyzed. Effect of externally applied magnetic field and twisted tape insert on convective heat transfer of water based ferrofluid flowing through a pipe was studied and examined. Working fluid is Fe3O4-Water. Ansys 2019 was used for simulation and analysis. Double pipe heat exchanger arrangement was modeled. Tube was modeled with consideration of, inner diameter of tube, di = 25mm and outer diameter of tube, do = 35 mm. Length of the tube was considered, L= 700 mm. Twisted tape of 5mm thickness and width of 10mm and 20mm was modelled. Meshing was done with the help of ICEM CFD and hooked up with Fluent 2019. Magnetic field was applied with the help MHD module in the fluent add on-model. External magnetic field intensity ranges from B=0-500 G. Reynolds number range of 250-800 was studied to understand its effect on heat transfer augmentation. The convective heat transfer was analyzed under both the condition, that are under the effect of with and without magnetic field. It was observed that ferrofluid responds to externally applied magnetic field. Under the application of constant magnetic field, heat transfer rate was observed to get increased by 12-14 % for without twisted tape arrangement and 18.7-21.4 % for with twisted tape arrangement for all Reynolds number range. This is because the under constant magnetic field application, dipoles of ferrofluid gets aligned in a same direction as that of direction of externally applied magnetic field, which leads transfer of heat at a faster rate as compared to the condition when dipoles are not aligned in a same direction, during the absence of magnetic field. Also due to twisted tape arrangement flow recirculation occurs. Significant improvement in heat transfer rate occurs due to disruption of velocity boundary layer, thermal boundary layer and increased flow mixing due to twisted tape

Keywords: Ferrofluid, Convective Heat transfer, External Magnetic field, Twisted Tape

Article published in International Journal of Current Engineering and Technology, Vol.10, No.3 (May/June 2020)