Studies on condensation over horizontal integral finned tubes

Abstract

Horizontal Integral-fin (HIF) tubes having two-dimensional (2D) rectangular or trapezoidal circumferential fins are commonly used in horizontal surface condensers, to enhance the shell side condensation heat transfer. Based on the literature survey, the present research program has been carried out with the following objectives: To develop a simple and easy to use correlation to find the condensing-side heat transfer coefficient during condensation of vapour over single HIF tubes. To study the prediction capability of the developed model for CFCs (chlorofluorocarbon), water and HCFC / HFC (hydrochlorofluorocarbon / hydrofluorocarbon) refrigerants. To develop a better technique for reducing the condensate flooding at the bottom of the HIF tubes (especially for a high surface tension fluid like water) as the condensate retention adversely affects the condensation heat transfer performance. To study the different flow patterns under various conditions to reduce the condensate inundation effects. The following are the major conclusions observed from the above studies: A simple empirical model with four non-dimensional equations and seven empirical constants has been developed for predicting the heat transfer performance during condensation of vapour on single HIF copper tubes with rectangular or trapezoidal fins. In addition, it is evident that by properly placing the circumferential drainage rings at strategic locations, it is possible to control the condensate drainage pattern, by which the condensate inundation effects could be minimized significantly in practical condensers. In case of bank of tubes, this technique can be extended to control the location of condensate drainage. It will leave the other regions of the tubes at the bottom rows unaffected and these regions of the tubes will function as the top row tubes without any condensate inundation effects. This will increase the overall heat transfer rate.