Investigation friction factor and heat transfer characteristics of turbulent flow inside the corrugated tube inserted with typical and V-cut twisted tapes

In present paper the effects of using typical twisted tape (TT) and V-cut twisted tape (VTT) on Nusselt number (Nu), friction factor (f) and thermal performance factor (η) inside corrugated tube in the turbulent flow are experimentally investigated despite the fact that the wall is under uniform heat flux. The experiments are conducted by twisted tapes with different twist ratio (y = 4.5, 6.07), depth and width ratios ranging (0.285–0.5) and Reynolds number varied from 5300 to 25,700 and water was as a working fluid. The obtained results show that the Nusselt number for corrugated tube that equipped with twisted tapes increases with increasing Reynolds number and is remarkable at high Reynolds Number while the friction factor is low. Moreover, the thermal performance factor for fluid increases with increasing Reynolds number and also the thermal performance factor for all states of VTT are higher than of TT. The new empirical correlations for Nusselt number, friction factor and thermal performance factor are predicted and compared with experimental data.