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Caractéristiques du transfert de chaleur lors de l'ébullition d'azote dans des tubes lisses ou garnis d'inserts métalliques enroulés.

Flow boiling heat transfer characteristics of nitrogen in plain and wire coil inserted tubes.

Auteurs : YUN R., HWANG J. S., CHUNG J. T., et al.

Type d'article : Article

Résumé

Boiling heat transfer characteristics of nitrogen were experimentally investigated in a stainless steel plain tube and wire coil inserted tubes. Wire coils having different coil pitches and wire thicknesses were inserted into a horizontally positioned plain tube, which had an inner diameter of 10.6 mm and a length of 1.65 m. The coil pitches were 18.4, 27.6, and 36.8 mm, and the wire thicknesses were 1.5, 2.0, and 2.5 mm. Tests were conducted at a saturation temperature of -191°C, mass fluxes from 58 to 105 kg/m2.s, and heat fluxes from 22.5 to 32.7 kW/m2. A direct heating method was used to apply heat to the test tube. The boiling heat transfer coefficients of nitrogen significantly decreased when the dryout occurred. Enhancement performance ratio (EPR), which is the ratio of heat transfer enhancement factor to pressure drop ratio, was used to evaluate the performance of the wire coil inserts. The maximum heat transfer enhancement of the wire coil inserted tubes over the plain tube was 174% with wire 3 having a twist ratio of 1.84 and a thickness ratio of 0.25. Wire 3-inserted tube showed the highest EPR among the tested tubes in this study. [Reprinted with permission from Elsevier. Copyright, 2006].

Détails

  • Titre original : Flow boiling heat transfer characteristics of nitrogen in plain and wire coil inserted tubes.
  • Identifiant de la fiche : 2007-1827
  • Langues : Anglais
  • Source : International Journal of Heat and Mass Transfer - vol. 50 - n. 11-12
  • Date d'édition : 06/2007

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