An experimental study of flow pattern and pressure drop for flow boiling inside microfinned helically coiled tube

Wenzhi Cui, Longjian Li, Mingdao Xin, Tien Chien Jen, Quan Liao, Qinghua Chen

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)

Abstract

In this paper, flow patterns and their transitions for refrigerant R134a boiling in a microfinned helically coiled tube are experimentally observed and analyzed. All the flow patterns occurred in the test can be divided into three dominant regimes, i.e., stratified-wavy flow, intermittent flow and annular flow. Experimental data are plotted in two kinds of flow maps, i.e., Taitel and Dukler flow map and mass flux versus vapor quality flow map. The transitions between various flow regimes and the differences from that in smooth straight tube have also been discussed. Martinelli parameter can be used to indicate the transition from intermittent flow to annular flow. The transition from stratified-wavy flow to annular or intermittent flow is identified in the vapor quality versus mass flux flow map. The flow regime is always in stratified-wavy flow for a mass flux less than 100 kg/m2 s. The two-phase frictional pressure drop characteristics in the test tube are also experimentally studied. The two-phase frictional multiplier data can be well correlated by Lockhart-Martinelli parameter. Considering the corresponding flow regimes, i.e., stratified and annular flow, two frictional pressure drop correlations are proposed, and show a good agreement with the respective experimental data.

Original languageEnglish
Pages (from-to)169-175
Number of pages7
JournalInternational Journal of Heat and Mass Transfer
Volume51
Issue number1-2
DOIs
Publication statusPublished - Jan 2008
Externally publishedYes

Keywords

  • Flow boiling
  • Flow pattern
  • Helically coiled tube
  • Microfin tube
  • Pressure drop

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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