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Article Dans Une Revue International journal of heat exchangers Année : 2002

Enhanced heat transfer in shell-side condensation

Résumé

The typical example of a non-compact heat exchanger is the shell-and-tube type. However, many attempts have been made to increase the compactness of such heat exchangers. Among these are the use of enhanced surface tubes in order to replace the smooth tubes still used. This paper describes the evolution of experimental observations and reviews the main models available in the literature for predicting the shell-side heat transfer coefficients for single tubes and tube bundles for pure fluids and azeotropic mixtures and for non-azeotropic mixtures. ln the case of condensation of pure fluids, heat transfer is controlled by the thermal resistance of the condensate film. The augmentation of condensation heat transfer can be achieved through thinning the condensate film. This can be obtained by draining the con densate via gravity, surface tension or, more rarely, electrical or other mechanical forces. Another way is to augment turbulent mixing of the condensate. In the case of mixtures, a supplementary resistance appears which is produced by the accumulation near the liquid vapour interface of a layer of the more volatile vapour whose condensation rate is lower than those of the other vapours. This resistance controls condensation heat transfer in most cases and the ways to augment heat transfer should be different. A large number of specifically designed enhanced surface tubes have been tested to find the best surface geometry for condensing either pure fluid or vapour mixture. These surfaces can be classified in three types: one-dimensional (1-D) surfaces (smooth tubes), two-dimensional (2-D) surfaces (with transverse plain fins) and three-dimensional (3-0) surfaces (with interrupted fins, spines, wires, etc ...). The 2-D and 3-D surfaces allow the surface tension effects to be enhanced. Moreover, other enhancement techniques can be employed by using promoting systems attached to the tubes such as drainage strips or external systems such as electric fields.
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Dates et versions

hal-00184109 , version 1 (07-02-2020)

Identifiants

  • HAL Id : hal-00184109 , version 1

Citer

André Bontemps, Mourad Belghazi. Enhanced heat transfer in shell-side condensation. International journal of heat exchangers, 2002, 3 (2), pp.201-239. ⟨hal-00184109⟩

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