Flow visualization of R32 in parallel-port microchannel tube

Research output: Contribution to journalArticle

Abstract

This paper presents visualization of two-phase flow of R32 in a parallel-flow microchannel tube with hydraulic diameter of 0.643 mm. Six visualization sections are installed in the facility, the same as in Li and Hrnjak (2017). Flow patterns are classified as: plug/slug, transitional, and annular flow. In plug/slug flow, a clear interface between liquid slug and vapor plug is observed. In transitional flow, the interface between slug and plug is broken and becomes a thick liquid ring and vapor bridge. In annular flow, only a liquid film is observed in the channel. The flow pattern map of R32 is reported. Mass flux changes from 50 to 300 kg-m−2s−1. The two-phase flow is generated by adding heat to subcooled refrigerant. The interface velocity and vapor plug length fraction (close to void fraction) are measured from high speed video. The velocity and vapor fraction agree to results based on a homogeneous assumption. When mass flux is 50 kg-m−2 s−1, the flow is always in plug/slug from vapor quality 0 to 1. Annular flow is observed at high quality when mass flux is higher than 100 kg-m−2 s−1. Transitional flow is observed when mass flux is higher than 150 kg-m−2 s−1, and it connects the plug/slug and annular flow patterns. Most flow pattern correlations fail to fit the measured flow pattern map. This is due to the difference in two-phase flow generation method and experimental conditions between this paper and the database used in correlations.

LanguageEnglish (US)
Pages1-11
Number of pages11
JournalInternational Journal of Heat and Mass Transfer
Volume128
DOIs
StatePublished - Jan 1 2019

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flow visualization
Flow visualization
plugs
microchannels
Microchannels
Flow patterns
annular flow
Vapors
tubes
Mass transfer
flow distribution
Two phase flow
vapors
two phase flow
Visualization
Parallel flow
Void fraction
liquids
Liquid films
Liquids

ASJC Scopus subject areas

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

Cite this

Flow visualization of R32 in parallel-port microchannel tube. / Li, Houpei; Hrnjak, Predrag Stojan.

In: International Journal of Heat and Mass Transfer, Vol. 128, 01.01.2019, p. 1-11.

Research output: Contribution to journalArticle

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