Heat Transfer in a Water Flow in Tubes with Ribbed Twisted Tape Inserts

The results of an experimental study of heat transfer in a water flow in a channel with a twisted tape insert with discrete ribs installed at an angle to the tape axis are presented. The experiments were performed in a straight smooth tube with an inner diameter of 10 mm. The tape inserts had a twist ratio of 2.5, 3, or 4 with a 180° rotation; the rib height ranged from 0.5 to 1.5 mm, the rib pitch was from 40 to 120 mm, and the rib angle was from 40 to 50° to the tape axis. The results of experiments in the mentioned range of geometries suggest that the ribbed tape inserts increase heat transfer by a maximum of 40% as compared with that in tubes with a twisted tape without ribs. The generalized correlation is given for the prediction of heat transfer in a Reynolds number range Re = 10 4 ‒2 × 10 5 .