Flow boiling heat transfer characteristics of nitrogen in plain and wire coil inserted tubes

Rin Yun, Jee Sang Hwang, Jin Taek Chung, Yong Chan Kim

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Boiling heat transfer characteristics of nitrogen were experimentally investigated in a stainless steel plain tube and wire coil inserted tubes. Wire coils having different coil pitches and wire thicknesses were inserted into a horizontally positioned plain tube, which had an inner diameter of 10.6 mm and a length of 1.65 m. The coil pitches were 18.4, 27.6, and 36.8 mm, and the wire thicknesses were 1.5, 2.0, and 2.5 mm. Tests were conducted at a saturation temperature of -191 °C, mass fluxes from 58 to 105 kg/m2 s, and heat fluxes from 22.5 to 32.7 kW/m2. A direct heating method was used to apply heat to the test tube. The boiling heat transfer coefficients of nitrogen significantly decreased when the dryout occurred. Enhancement performance ratio (EPR), which is the ratio of heat transfer enhancement factor to pressure drop ratio, was used to evaluate the performance of the wire coil inserts. The maximum heat transfer enhancement of the wire coil inserted tubes over the plain tube was 174% with wire 3 having a twist ratio (p/Dw) of 1.84 and a thickness ratio (t/Dw) of 0.25. Wire 3-inserted tube showed the highest EPR among the tested tubes in this study.

Original languageEnglish
Pages (from-to)2339-2345
Number of pages7
JournalInternational Journal of Heat and Mass Transfer
Volume50
Issue number11-12
DOIs
Publication statusPublished - 2007 Jun 1

    Fingerprint

Keywords

  • Boiling heat transfer
  • Dryout
  • EPR
  • Nitrogen
  • Wire coil

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes
  • Energy(all)
  • Mechanical Engineering

Cite this