Experimental investigation on flooding in a fluted tube with and without a twisted insert

Yong Tae Kang, Roger Stout, Richard N. Christensen

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Experimental flooding data were obtained for a smooth tube and a fluted tube with and without a twisted insert. Fluted tubes have been used to enhance both heat and mass transfer for many thermal systems including absorption heat pump systems. A plastic auger (twisted insert) was inserted in the fluted tube to increase heat and mass transfer. The effects of the twisted insert and angle of inclination on the flooding were examined. A water and ethyl alcohol solution (simulating an ammonia-water solution) flows downward in the fluted tube while air flows counter current in an upward direction. The onset of flooding and the flooding mechanism were analyzed at variable angles of inclination by visual observation. The experimental results showed that the effect of the twisted insert on the flooding curve decreased as the inclination angle varied from a horizontal to a vertical position. The effect of the enhanced surface was not affected by the inclination angle. The flooding velocity was the highest between the inclination angle of 20 and 50 depending on the liquid mass flow rates for the smooth tube, between 20 and 55 for the fluted tube without the insert, and between 40 and 60 for the superficial liquid velocities of 42.4 m/hr and lower for the fluted tube with an insert. The enhancement factor for the flooding velocity was obtained for the fluted tubes with/without inserts. Flooding correlations were developed as a function of inclination angle for the smooth tube, and the fluted tube with/without a twisted insert with an error band of ± 8.5%, ± 5.0% and ± 10.0%, respectively.

Original languageEnglish
Pages (from-to)111-129
Number of pages19
JournalJournal of Enhanced Heat Transfer
Volume4
Issue number2
Publication statusPublished - 1997 Dec 1
Externally publishedYes

Fingerprint

inserts
tubes
Mass transfer
inclination
Heat transfer
Heat pump systems
Die casting inserts
Water
Liquids
Ammonia
Ethanol
Flow rate
Plastics
Air
mass transfer
heat transfer
heat pumps
visual observation
mass flow rate
air flow

Keywords

  • Air-water and ethyl alcohol
  • Enhancement factor
  • Flooding velocity
  • Helically fluted tube
  • Inclination angle
  • Twisted insert

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes
  • Physical and Theoretical Chemistry
  • Mechanical Engineering

Cite this

Experimental investigation on flooding in a fluted tube with and without a twisted insert. / Kang, Yong Tae; Stout, Roger; Christensen, Richard N.

In: Journal of Enhanced Heat Transfer, Vol. 4, No. 2, 01.12.1997, p. 111-129.

Research output: Contribution to journalArticle

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