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Document IIF

Étude numérique des effets de la mouillabilité sur les performances d’un éjecteur au CO2.

Numerical study on effects of wettability on performances of CO2 ejector.

Auteurs : LIU F., YANG W., JIA S., LI P.

Type d'article : Article de la RIF

Résumé

Inner wall surface wettability could affect ejector performances, however, no-slip wall boundary conditions were mostly assumed in CO2 ejector simulation studies. In this study, we introduced velocity slip boundary condition into the 3D heterogeneous mixture model for a two-phase CO2 ejector, by using different apparent contact angle at the inner wall of mixing chamber, motive nozzle or diffuser. Numerical simulation results show that the inner wall wettability of mixing chamber and diffuser affects flow and mass transfer in a CO2 ejector significantly, while the inner wall wettability of motive nozzle affects ejector performances very slightly. As apparent contact angle increases from 5° to 175°, resulting in the change of slip condition from negative slip to no-slip then to positive slip, velocity in mixing chamber increases, pressure in mixing chamber decreases, expansion angle after motive nozzle outlet decreases, thus backflow vortices become smaller then disappear. This leads to an increase in suction mass flow rate, and entrainment ratio can be enhanced over 15 %. Correlations between entrainment ratio and apparent contact angle at the wall of different parts in ejector were developed. As the wall wettability changes from hydrophilic to superhydrophobic, the variation trends of ejector performances are similar under different operating conditions with motive nozzle inlet in the supercritical, near-critical, and subcritical regions. This study is helpful to understand flow mechanisms inside the CO2 ejector with different wall wettability, and provides a new approach to improve the performances of a two-phase CO2 ejector by changing wall surface wettability.

Documents disponibles

Format PDF

Pages : 267-286

Disponible

  • Prix public

    20 €

  • Prix membre*

    Gratuit

* meilleur tarif applicable selon le type d'adhésion (voir le détail des avantages des adhésions individuelles et collectives)

Détails

  • Titre original : Numerical study on effects of wettability on performances of CO2 ejector.
  • Identifiant de la fiche : 30033559
  • Langues : Anglais
  • Source : International Journal of Refrigeration - Revue Internationale du Froid - vol. 171
  • Date d'édition : 03/2025
  • DOI : http://dx.doi.org/10.1016/j.ijrefrig.2025.01.015

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