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Transfert de chaleur lors de l'ébullition libre, chute de pression et configuration de l'écoulement du CO2 et du R-410A.

Flow boiling heat transfer, pressure drop, and flow pattern for CO2 and R-410A at low temperatures.

Auteurs : PARK C. Y., HRNJAK P. S.

Résumé

CO2, R-410A, and R-22 flow boiling heat transfer coefficient, pressure drop, and flow pattern are investigated in the horizontal smooth tube of 6.1 mm inner diameter. Flow boiling heat transfer coefficients are measured at the constant wall temperature conditions, while pressure drop measurement and flow visualization are carried out at adiabatic conditions. This experimental study is performed at evaporation temperatures of -15 and -30°C, mass flux from 100 to 400 kg/m2.s, and heat flux from 5 to 15 kW/m2 for vapour qualities ranging from 0.1 to 0.8. The comparison of heat transfer coefficients for CO2, R-410A, and R-22 is presented at various heat fluxes, mass fluxes, and evaporation temperatures. The difference of coefficients for each refrigerant is explained with the Gungor and Winterton (1986) correlation based on the thermophysical properties of refrigerants. Pressure drop for CO2, R-410A, and R-22 at various mass fluxes, evaporation temperatures and qualities is presented in this paper. From the comparison of the predicted and measured values, several correlations are proposed to predict CO2 and R-410A flow boiling heat transfer and pressure drop. The observed two-phase flow patterns for CO2 and R-410A are presented and compared with flow pattern maps. Most of the flow patterns can be determined by the Weisman et al. (1979) flow pattern map.

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Format PDF

Pages : ICR07-B1-1634

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Détails

  • Titre original : Flow boiling heat transfer, pressure drop, and flow pattern for CO2 and R-410A at low temperatures.
  • Identifiant de la fiche : 2008-0038
  • Langues : Anglais
  • Source : ICR 2007. Refrigeration Creates the Future. Proceedings of the 22nd IIR International Congress of Refrigeration.
  • Date d'édition : 21/08/2007

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