Document IIF

Régime d'écoulement annulaire dans les microcanaux circulaires : chutes de pression diphasiques.

Two-phase pressure drops in the annular flow regime in circular microchannels.

Résumé

The paper presents an experimentally validated model for pressure drop in the annular flow regime during condensation of refrigerant R134a in horizontal microchannels. Two-phase pressure drops were measured in five circular channels ranging in hydraulic diameter from 0.5 to 4.91 mm. For each tube under consideration, pressure drop measurements were first taken over the entire range of qualities from 100% vapour to 100% liquid for five different refrigerant mass fluxes between 150 and 750 kg/m2.s. Results from previous work by the authors on condensation flow mechanisms in microchannel geometries were used to identify the data that correspond to the annular flow regime. The experimental results were compared with the predictions of conventional two-phase pressure drop correlations, and also with modifications to these correlations. The agreement with these available models was not particularly good. Therefore, a model for predicting pressure drops in this regime was developed by determining the ratio of the friction factor at the gas-liquid interface to the liquid-phase friction factor. This interfacial friction factor was then used to estimate the two-phase frictional pressure drop. The model developed in the paper predicts 84% of the data within plus or minus 20%. The effect of hydraulic diameter on condensation pressure drop was also demonstrated.

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Détails

  • Titre original : Two-phase pressure drops in the annular flow regime in circular microchannels.
  • Identifiant de la fiche : 2004-2724
  • Langues : Anglais
  • Source : 21st IIR International Congress of Refrigeration: Serving the Needs of Mankind.
  • Date d'édition : 17/08/2003

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