Some aspects of film condensation of steam on finned tubes

Abstract

Heat-transfer measurements were made for filmwise condensation of steam on smooth tubes and finned tubes with rectangular-shaped fins. The influence of fin root diameter on a single horizontal finned tube was examined by taking data for two families of tubes whose fin root diameters were 12.7 and 19.05 mm. Each family of tubes had fins that were 1 mm thick and 1 mm high but with fin spacings of 0.25, 0.50, 1.0, 1.5, 2.0, and 4.0 mm. To compare results being obtained in a concurrent research project with Queen Mary College (University of London), data was collected on two tubes whose fin root diameters were 12.7 mm and which had thicknesses of 0.5 mm, fin heights of 1.59 mm, and which had fin spacings of 1.0 mm. A comparison of the enhancement ratios (based on constant vapor-side temperature drop) with past Naval Postgraduate School (NPS) data showed good agreement. The apparatus was then modified in order to study the effects of condensate inundation. Preliminary flow visualization studies of the condensate motion were made. On finned tubes, the condensate falling on the tubes has a tendency to be channeled between fins and does not spread out axially as occurs on smooth tubes.