Two-phase flow characterization for metal concentric tubes with capacitance measurement

Hequn Liu, Wenzhe Li, Jinqing Peng, Lizhi Wang, Haobo Jiang, Long Huang, Houpei Li*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The two-phase flow characteristics for the concentric tube would be different to a plain tube. But the existing research focused on the two-phase flow in circular tubes, without concentric structures. The purpose of this paper was to reveal the two-phase flow characteristics for R134a in both horizontal and vertical upward flow between two concentric tubes by capacitance sensors. The capacitive signals corresponding to different vapor qualities were measured with the mass fluxes from 18.37 kg m−2 s−1 to 64.31 kg m−2 s−1. The experimental data showed that the value of the time-averaged capacitive signal was mainly determined by the vapor quality. The measured capacitance was independent of the mass flux and electrode width, but greatly influenced by the flow direction. The result in horizontal flow was flatter when the fluid was closer to the single-phase and steeper at moderate vapor quality (from 0.1 to 0.9), while it was close to a straight line in vertical upward flow. Moreover, the capacitive signals had oscillation characteristics. By the probability density function, it was found that the amplitude features and oscillation levels were related to the flow patterns. The amplitude degree reflected the stability of the two-phase flow. The oscillation levels could be explained by the flow pattern transition. The corresponding relationship between flow patterns and oscillation characteristics was discovered, which could provide more information for the identification of flow patterns.

Original languageEnglish
Pages (from-to)287-297
Number of pages11
JournalInternational Journal of Refrigeration
Volume156
DOIs
Publication statusPublished - Dec 2023

Keywords

  • Capacitance sensor
  • Flow characteristic
  • Flow pattern
  • Two-phase flow

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