An overview of condensation heat transfer on horizontal tube bundles

This paper presents an overview of the heat transfer characteristics of shell and tube condensing heat exchangers, particularly for the case of downward flowing condensing vapour on tube bundles. In the process, over 70 papers are reviewed where, the condensation on the outside of single tubes and tube bundles is studied. This paper describes variations in experimental observations made by the researchers and simultaneously the effects of surface geometry, condensate inundation, vapour shear, and gravity are quantified. The review reveals that accurate models are available in the literature for predicting condensing heat transfer coefficients for single tubes (smooth and integral-finned) under both stationary vapour and vapour shear conditions. However there is a need to develop theoretical models for enhanced tube surfaces operating under both single and tube bank conditions. Also the application of heat transfer models incorporating the effects of vapour shear in tube banks (both smooth and finned tubes) is still tentative due to the difficulty in predicting the velocity distribution through the tube bank. (C) 1999 Elsevier Science Ltd. All rights reserved.