A critical review of heat transfer and pressure drop in a spirally grooved tube with twisted tape insert

Abstract

In this paper, experimentally determined pressure drop, heat transfer characteristics and performance enhancement parameters of flow of water in a 75-start spirally grooved tube with twisted tape insert are presented. Fully turbulent ranges (3000-7000) of Reynolds numbers have been considered. The grooves are clockwise with respect to the direc­tion of flow. Compared to smooth tube, the heat transfer enhancement due to spiral grooves is further augmented by inserting twisted tapes having twist ratios . It is found that the direction of twist (clockwise and anticlockwise) influences the thermo-hydraulic characteristics. Con­stant pumping power comparisons with smooth tube characteristics show that in spirally grooved tube with and without twisted tape, heat transfer increases moderately in turbu­lent range of Reynolds numbers. However, for the bare spiral tube and for spiral tube with anticlockwise twisted tape ( ), reduction in heat transfer is noticed over a transition range of Reynolds numbers.Heat transfer and pressure drop are compered with plain tube results and performance enhancement parameters are obtained.