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Une méthode pour prévoir le taux de vide de l'écoulement diphasique de vapeur et de liquide à l'intérieur d'un tube à micro-ailettes.

A method for predicting void fraction of vapour-liquid two-phase flow inside a microfin tube.

Auteurs : KOYAMA S., LEE J. D., YONEMOTO R., et al.

Résumé

This paper deals with experiments and a prediction method for the void fraction of R134a vapour-liquid two-phase flow in horizontal smooth and microfin tubes on adiabatic condition. The void fraction is measured by the quick closing valve method. The smooth tube tested is 1024 mm in length and 7.52 mm in inside diameter. The microfin tube tested is 1015 mm in length and 8.86 mm in mean inside diameter; the fin height is 0.18 mm, the helix angle of fins is 25 degrees and the total number of fins is 70. The experiments were carried out in the range of vapour quality from 1 to 96%, where the pressure was kept at 1.2 and 0.8 MPa and the mass flow rate was kept at 20 and 40 kg/h. It was confirmed that the void fraction in the microfin tube is lower than that of smooth tube in any quality. The void fraction prediction method consists of a stratified-annular flow model and an annular flow model. For the stratified-annular flow model is assumed that most of liquid flows at the bottom of tube and all the grooves are filled with additional liquid. In the case of an annular flow model, it is assumed that all grooves are filled with liquid uniformly. The momentum equations are constructed for each region and solved numerically. The predicted results of void fraction are relatively in good agreement with the present experimental data for microfin tubes.

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Détails

  • Titre original : A method for predicting void fraction of vapour-liquid two-phase flow inside a microfin tube.
  • Identifiant de la fiche : 2005-0104
  • Langues : Anglais
  • Source : 21st IIR International Congress of Refrigeration: Serving the Needs of Mankind.
  • Date d'édition : 17/08/2003

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