Effect of Fin Spacing on the Performance of Horizontal Integral-Fin Condenser Tubes

Abstract

The dependence of heat transfer performance on fin spacing has been investigated for condensation of steam on horizontal integral-fin tubes. Thirteen tubes have been used with rectangular section fins having the same width and height (0.5 mm and 1.6 mm) and with fin pitch varying from 1.0 mm to 20.5 mm. For comparison, tests were made using a plain tube having the same inside diameter and an outside diameter equal to that at the root of the fins for the finned tubes. All tests were made at near-atmospheric pressure with vapor flowing vertically downward with velocities between 0.5 m/s and 1.1 m/s. The observed heat transfer enhancement for the finned tubes significantly exceeded that to be expected on grounds of increased area. Plots of enhancement against fin density were repeatable and showed local maxima and minima. The dependence of enhancement on fin density did not depend appreciably on vapor velocity or condensation rate for the ranges used. The maximum vapor-side enhancement (i.e., vapor-side heat transfer coefficient of finned tube/vapor-side coefficient for plain tube) was found to be around 3.6 for the tube with a fin spacing of 1.5 mm.

Condensation Heat Transfer on Geometrically Enhanced Horizontal Tube: A Review

“…For both larger and smaller diameters, the best-performing integral-fin tubes were found with fin spacings of 1.5, 1.0 and 0.5mm for steam, ethylene glycol and R-113, respectively. They compared their own experimental data with the indirectly obtained experimental data of earlier investigators [24,27,28,30] and a satisfactory agreement was found.…”

“…The saw-toothed tube gave the best heat-transfer enhancements (defined as heat-transfer coefficient for saw-toothed tube based on fin-tip diameter divided by the heat-transfer coefficient for a smooth tube at the same vapour-side, temperature difference) for both fluids which was 9.0 and 6.1 for R-113 and methanol, respectively. Yau et al [24] reported an experimental study of dependence of heat transfer on fin spacing for the condensation of steam on horizontal integral-fin tubes. Thirteen tubes with rectangular fins having a thickness of 0.5mm and a height of 1.6 mm were tested by systematically varying fin spacing from 0.5 to 20mm.…”

“…The effect of fin spacing was investigated on the same set of tubes as used by Yau et al [14,24] with the inclusion of a new integral-fin tube with a fin spacing of 0.25mm. Predetermined coolant-side correlation and a modified Wilson plot method were used to evaluate the vapour-side, heat-transfer coefficients.…”

Condensation of pure refrigerants R12, R134a and their mixtures on a horizontal tube with capillary structure: An experimental study

“…In experiments, either the heat transfer was measured using single tubes [25, 26, 31-34, 36, 37, 42, 43, 46, 51, 54, 55, 57, 58] and tube bundles [12,20,22,28,45,[47][48][49][50]56], or capillary phenomena and condensate retention in the lower bottom tube region [31][32][33][34]37] were analysed. As was to be expected, flooding of the lower tube portion is influenced by fin geometry and physical properties of condensate.…”

A semi-empirical model for free-convection condensation on horizontal pin–fin tubes

“…A significant number of experimental investigations have been reported on free-convection condensation heat-transfer on horizontal integral-fin tubes; see for example [1][2][3][4][5][6][7][8][9][10][11]. During the condensation process, liquid retained on the lower part of tube insulates the fin flanks and root from heat transfer, This condensate retention on integral-fin tubes was first observed by Katz et al [12] and afterwards experimentally investigated by many other investigators for a wide range of fluid and tube combinations [1,3,[13][14][15].…”