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Transfert de chaleur lors de l'ébullition sous-refroidie de R407C et caractéristiques bullaires associées dans un conduit annulaire étroit.

Subcooled flow boiling heat transfer of R407C and associated bubble characteristics in a narrow annular duct.

Auteurs : CHEN C. A., CHANG W. R., LI K. W., et al.

Type d'article : Article

Résumé

An experiment is conducted here to investigate how the channel size affects the subcooled flow boiling heat transfer and the associated bubble characteristics of refrigerant R407C in a horizontal narrow annular duct with the gap of the duct fixed at 1.0 and 2.0 mm. The measured boiling curves indicate that the temperature overshoot at ONB is relatively significant for the subcooled flow boiling of R407C in the duct. Besides, the subcooled flow boiling heat transfer coefficient increases with a reduction in the duct gap, but decreases with an increase in the inlet liquid subcooling. Moreover, raising the heat flux imposed on the duct can cause a significant increase in the boiling heat transfer coefficients. However, the effects of the refrigerant mass flux and saturated temperature on the boiling heat transfer coefficient are slighter. Visualization of the subcooled flow boiling processes in the duct reveals that the bubbles are suppressed to become smaller and less dense by raising the refrigerant mass flux and inlet subcooling. Raising the imposed heat flux, however, produces positive effects on the bubble population, coalescence and departure frequency. Meanwhile, the present heat transfer data for R407C are compared with the R134a data measured in the same duct and with some existing correlations. We also propose empirical correlations for the present data for the R407C subcooled flow boiling heat transfer and some quantitative bubble characteristics such as the mean bubble departure diameter and frequency and the active nucleation site density. [Reprinted with permission from Elsevier. Copyright, 2009].

Détails

  • Titre original : Subcooled flow boiling heat transfer of R407C and associated bubble characteristics in a narrow annular duct.
  • Identifiant de la fiche : 2009-1919
  • Langues : Anglais
  • Source : International Journal of Heat and Mass Transfer - vol. 52 - n. 13-14
  • Date d'édition : 06/2009
  • DOI : http://dx.doi.org/10.1016/j.ijheatmasstransfer.2009.01.027

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