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Coefficient moyen de transfert de chaleur pour l'ébullition en écoulement du R134a et du R123 à l'intérieur de tubes lisses et de tubes à surface augmentée (projet RP-1316).

Average heat transfer coefficient for pool boiling of R134a and R123 on smooth and enhanced tubes (RP-1316).

Auteurs : GORGY E., ECKELS S.

Type d'article : Article

Résumé

This paper presents information about nucleate pool boiling of R134a and R123 on TBIIHP and TBIILP tubes, respectively, as well as on smooth tubes. This is the first phase of ASHRAE project RP-1316, Experimental evaluation of heat transfer impacts of tube pitch in a highly enhanced surface tube bundle. Data were taken at a saturation temperature of 4.44°C (40°F). The test tubes’ outer diameter was 19.05 mm (0.75 in.) and had lengths of 1 m (39.37 in.). Tubes were water heated with an insert in the water passage. A new analytical method known as enthalpy-based heat transfer analysis (EBHT) was introduced and used to determine the refrigerant heat transfer coefficient. The heat flux range was 4–135 kW/m² (1269–42,823 Btu/h·ft²) for R134a on TBIIHP and 5–60 kW/m² (1586–19,033 Btu/h·ft²) for R123 on TBIILP. The resulting heat transfer coefficient range for R134a on TBIIHP was 6270–23,268 W/m²·°C (1105–4100 Btu/h·ft²·°F) and 6748–23,338 W/m²·°C (1189–4113 Btu/h·ft²·°F) for R123 on TBIILP. The present study provided one of the widest heat flux ranges studied with this type of tubes and showed significant structure to the pool boiling curve, which had not been traditionally observed. The experimental data of the smooth tubes were compared against the Cooper and Stephan-Abdelsalam correlations. The Cooper correlation provided a better fit with the experimental data, with an average uncertainty of 27% for R123 and 16% for R134a.

Détails

  • Titre original : Average heat transfer coefficient for pool boiling of R134a and R123 on smooth and enhanced tubes (RP-1316).
  • Identifiant de la fiche : 30002578
  • Langues : Anglais
  • Source : HVAC&R Research - vol. 16 - n. 5
  • Date d'édition : 09/2010
  • DOI : http://dx.doi.org/10.1080/10789669.2010.10390926

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