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Influence des tubes en U dans un refroidisseur d'air au frigoporteur sur le profil de température du frigoporteur et le transfert de chaleur en aval sous des conditions d'écoulement laminaire.

The influence of secondary refrigerant air chiller U-bends on fluid temperature profile and downstream heat transfer for laminar flow conditions.

Auteurs : CLARKE R., FINN D. P.

Type d'article : Article

Résumé

This paper describes numerical investigations, using computational fluid dynamics, conducted to examine the heat transfer mechanisms by which air-chiller U-bends cause enhanced downstream internal convection, where single phase secondary refrigerants under laminar conditions are employed as the heat exchanger fluid. The numerical model, created using FLUENT, consists of a single heat exchanger tube pass incorporating an inlet pipe, a U-bend and an outlet pipe. The model was validated using experimental data from the literature. Numerical investigations indicate that within the U-bend, secondary flows partially invert temperature profiles resulting in a significant localised decrease in average fluid temperature at the pipe surface. As a result, downstream heat transfer enhancement is observed, the magnitude of which can exceed that typical of a pipe combined entry condition in some circumstances by greater than 20% for up to 20 pipe diameters downstream. Heat transfer enhancement was found to increase with increasing U-bend radius, but to decrease with increasing heat exchanger pipe radius and internal Reynolds number. A simple technique based on quantification of the degree of temperature inversion at the U-bend is proposed which provides a mechanism by which heat transfer enhancement can be estimated. [Reprinted with permission from Elsevier. Copyright, 2007].

Détails

  • Titre original : The influence of secondary refrigerant air chiller U-bends on fluid temperature profile and downstream heat transfer for laminar flow conditions.
  • Identifiant de la fiche : 2008-1290
  • Langues : Anglais
  • Source : International Journal of Heat and Mass Transfer - vol. 51 - n. 3-4
  • Date d'édition : 02/2008

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