Experiment and visualization on R134a upward flow in the vertical header of microchannel heat exchanger and its effect on distribution

Yang Zou, Pega S. Hrnjak

Research output: Contribution to journalArticlepeer-review

Abstract

R134a upward flow in four different vertical headers and its effect on R134a distribution into parallel microchannel tubes were investigated experimentally. R134a was provided into the header by (5 or 10) tubes in the bottom pass and exits through the (5 or 10) tubes in the top pass representing the flow in the heat pump mode of reversible systems. The inlet quality was varied from 0.2 to 0.8, and the mass flux from 92.26 to 276.79 kg m 2 s 1 per tube. The best distribution was at high flux and low quality. Experiment and visualization reveals the flow pattern effect in terms of homogeneity and momentum: churn flow has better distribution than separated flow since the two-phase mixture is more homogeneous; distribution is better at high mass flux in the header (by increasing mass flow rate, tubes number and/or tubes protrusion) because the higher momentum liquid can reach the top exit tube.

Original languageEnglish (US)
Pages (from-to)124-134
Number of pages11
JournalInternational Journal of Heat and Mass Transfer
Volume62
Issue number1
DOIs
StatePublished - 2013

Keywords

  • Microchannel heat exchanger
  • Refrigerant distribution
  • Two-phase flow
  • Vertical header

ASJC Scopus subject areas

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

Fingerprint Dive into the research topics of 'Experiment and visualization on R134a upward flow in the vertical header of microchannel heat exchanger and its effect on distribution'. Together they form a unique fingerprint.

Cite this