An Analysis of Film Condensation on a Horizontal Wire-Wrapped Tube

Abstract

The paper gives a provisional analysis of heat transfer during laminar film condensation on a horizontal, wire-wrapped tube. This preliminary report is based on an approximate, partly empirical, earlier solution1. The present work includes capillary condensate retention between the wire and tube determined using the approach of Masuda and Rose2 for condensation on integral-finned tubes. The final result is given in the form of a simple equation for the enhancement ratio (heat transfer for the wire-wrapped tube divided by the Nusselt value for the plain tube with the same vapour-to-surface temperature difference). The theoretical enhancement ratio depends only on the tube and wire diameters and the pitch of the winding, as well as the surface tension and density of the condensate, and is independent of the vapour-to-surface temperature difference. The expression for enhancement may readily be used to optimize the geometric variables for condensation of a given fluid. Comparison with limited available experimental data is inconclusive and indicates the need for further experimental work and scrutiny of approximations used in the model.