Heat transfer enhancement in a curved tube by using twisted tape insert and turbulent nanofluid flow

Abstract

In this experimental study, twisted tape insert and nanofluid turbulent flow (passive techniques) are considered to increase the heat transfer in the curved tube. The curved tube and twisted tape are fabricated from the copper. The test section (curved tube) is submerged inside a pool filled with hot water. To prepare water/Al2O3 nanofluid, a three-step procedure is utilized. The influences of volume flow rate, nanoparticles concentration, and twisted tape insert on the convective heat transfer coefficient, Nusselt number, and Darcy friction factor are studied. The results show that the curved tube with twisted tape insert improves the convective heat transfer coefficient up to 31%. But enhancing Al2O3 concentration from 0 to 1% increases convective heat transfer coefficient up to 21%. On the other hand, the twisted tape and adding nanoparticle affect Darcy friction factor, and it is greater than that without twisted tape and base fluid. In addition, the Darcy friction factor declines by increment of volume flow rate. Ultimately, the current article presents a new twisted tape as passive enhancement technique.