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Local bundle boiling heat transfer coefficients on an integral finned tube bundle.

Author(s) : ROBINSON D. M., THOME J. R.

Type of article: Article

Summary

Experiments have been performed for evaporation of refrigerants R134a and R507A on the outside of a horizontal bundle of integral finned tubes. Hot water flowing through the tubes is used as the heat source. Water temperature measurements were made at numerous axial locations within the tubes to obtain the water's temperature profile and thus measure twelve local heat transfer coefficients simultaneously in the bundle. Pool boiling tests to measure the corresponding nucleate boiling curves were also performed. Tests were conducted with a 20-tube bundle over the following range of heat flux (2 to 50 kW/m2), mass flux (3 to 29 kg/(m2 s)), and vapor quality (8 to 82%). The bundle test results showed a significant contribution of convection from rising bubbles to the heat transfer process, with local heat transfer coefficients as large as two times those of nucleate pool boiling in the case of R134a, but on average a 34% increase. R507A showed significantly less benefit due to convection, averaging only a 10% increase.

Details

  • Original title: Local bundle boiling heat transfer coefficients on an integral finned tube bundle.
  • Record ID : 2004-2720
  • Languages: English
  • Source: HVAC&R Research - vol. 10 - n. 3
  • Publication date: 2004/07
  • Document available for consultation in the library of the IIR headquarters only.

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