Void fraction and flow regime of in-tube condensation in a vapor-compression system

Jiange Xiao, Pega Hrnjak

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In vapor-compression systems, superheated vapor condenses with temperature gradient. A “3-zone” (superheated, two-phase and subcooled) approach is not fully representative of the process because condensation happens earlier and later than bulk quality 1 and 0 respectively. The new approach, which is “5-zone” (additional condensing superheated and condensing subcooled), addresses those issues by capturing the non-equilibrium effects. Void fraction and flow regime measured in 4 and 6 mm smooth horizontal round tubes are used to validate the new approach in the range: mass flux from 50 to 400 kg m-2 s-1; heat flux 5 to 15 kW m-2; condensing temperatures 30 and 50oC. The refrigerants explored are R32, R134a, R1234ze(E), R245fa and R1233zd(E). Comparing to the “3-zone” approach, the new void fraction correlation and flow regime map expend the prediction range by finding the real onset and end of condensation, providing grounds for new heat transfer and pressure drop models.

Original languageEnglish (US)
Title of host publicationICR 2019 - 25th IIR International Congress of Refrigeration
EditorsVasile Minea
PublisherInternational Institute of Refrigeration
Number of pages9
ISBN (Electronic)9782362150357
StatePublished - 2019
Event25th IIR International Congress of Refrigeration, ICR 2019 - Montreal, Canada
Duration: Aug 24 2019Aug 30 2019

Publication series

NameRefrigeration Science and Technology
ISSN (Print)0151-1637


Conference25th IIR International Congress of Refrigeration, ICR 2019


  • Condensing Superheated Region
  • Flow Regime Map
  • Non-Equilibrium
  • Vapor-Compression System
  • Void Fraction

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering
  • Mechanical Engineering
  • Condensed Matter Physics


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