Effect of full length twisted tape inserts on heat transfer and friction factor enhancement with Fe3O4 magnetic nanofluid inside a plain tube: An experimental study

Abstract: Turbulent convective heat transfer and friction factor characteristics of magnetic Fe3O4 nanofluid flowing through a uniformly heated horizontal circular tube with and without twisted tape inserts are estimated experimentally. Experiments are conducted in the particle volume concentration range of 0< φ <0.6%,twisted tape inserts of twist ratio in the range of 0< H/D <15and Reynolds number range of 3000<Re<22000. Heat transfer and friction factor enhancement of 0.6% volume concentration of Fe3O4 nanofluid in a plain tube with twisted tape insert of twist ratio H/D=5 is 51.88% and 1.231 times compared to water flowing in a plain tube under same Reynolds number. Generalized regression equation is presented for the estimation of Nusselt number and friction factor for both water and Fe3O4 nanofluid in a plain tube and with twisted tape inserts under turbulent flow condition. [Copyright &y& Elsevier]