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Prévision de l'absorption du frigorigène et du démarrage de la convection naturelle dans de l'huile lubrifiante.

Prediction of refrigerant absorption and onset of natural convection in lubricant oil.

Auteurs : BARBOSA J. R., THOMA S. M., NETO M. A. M.

Type d'article : Article, Article de la RIF

Résumé

Refrigerant absorption and mixing in lubricant oil are important in the design of refrigeration compressors and refrigeration systems. Experimental work is reported on absorption of R-134a vapour through the top interface of an initially stagnant layer of pure lubricant oil. Since the liquid refrigerant is heavier than the oil, mixing is enhanced due to natural mass convection. In this paper, the behaviour of the liquid temperature during absorption is described based on measurements carried out in a test rig consisting of a transparent 70 mm ID, 150 mm long, vertical glass tube through which absorption can be directly observed. Transient liquid temperatures were measured at three different heights in the test section (two in the vapour, one in the liquid). The experimental work is complemented by a theoretical analysis of the critical time for the onset of mass transfer induced Rayleigh instability. The model is based on a critical mass transfer Rayleigh number criterion widely reported in the literature and takes into account the variation of physical properties in the liquid layer. The critical time for the onset of natural mass convection increases with decreasing system pressure as a result of a lower equilibrium concentration at the vapour-liquid interface.

Documents disponibles

Format PDF

Pages : 1231-1240

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 : Prediction of refrigerant absorption and onset of natural convection in lubricant oil.
  • Identifiant de la fiche : 2008-2427
  • Langues : Anglais
  • Source : International Journal of Refrigeration - Revue Internationale du Froid - vol. 31 - n. 7
  • Date d'édition : 11/2008

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