Parametric effect of diverging perforated cones on the thermo-hydraulic performance of a heat exchanger tube

In the present work, conical frustums (d/D = 0.3) are used as turbulators to form an insert of a heat exchanger tube. Both the perforated and imperforated conical inserts in a diverging arrangement (DR arrangement) are experimentally studied. The effects of the parameters like pitch ratio (p/D), the number of perforated holes (N), and relative location of perforations (x/L) on thermal and fluid characteristics are investigated. The results indicate that the inserts are effective in mixing the fluid at a lower temperature in the core region with the fluid at a higher temperature near the wall. Perforation and its effect on thermo-hydraulic performance are critically examined in the study. Perforations near the small-end diameter of the conical insert are found to be effective in terms of reduction in frictional loss and also increment of heat transfer near the wall region. The maximum thermo-hydraulic performance (η) is found to be 1.38 for the perforated conical insert in the diverging arrangement (PDR) having d/D = 0.3, p/D = 2, x/L = 0.5, N = 4 at the Reynolds number of 6258.