Evaluation of a tube equipped with different inserts: competition between improvements in heat transfer versus increase in pressure drop

Abstract

This study evaluated the efficacy of different inserts incorporation into the simple tube on the rate of improvement in heat transfer as well as the intensification in the pressure drop. The results were presented in four sections. In the first and second sections, the effects of adding wire coil and twisted tape were examined. The third section investigated the effects of disk, trapezoidal, and rhombic turbulators. In the last section, the results of the three techniques were compared. At Reynolds number within the range of 5000–25,000 (turbulent flow), the Nusselt number improved by 150% to 200% as well as the friction factor intensified by 200% to 300%, owing to the incorporation of wire coil into the simple tube. For twisted tape, it was found that by adding the angled blade to the twisted tape, the Nusselt number enhanced up to 11%. For three turbulators, owing to the installation disk turbulator, the average Nusselt number has improved by 190%. For rhombus and trapezoidal turbulators, the rate of improvement in heat transfer was reported to be 90% and 30%, respectively. Comparison between the three types of inserts revealed that the disk turbulator performs better than the wire coil and twisted tape.