Distribution function for reversible microchannel heat exchanger with vertical headers - Considering the effects of inlet conditions, geometries and fluid properties

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

Abstract

Refrigerant maldistribution deteriorates microchannel evaporator performance because it creates unwanted superheated region. The objective of this study is to explore what affects distribution in the vertical header and how to model distribution. Two-phase R245fa, R134a, R410A or R32 is circulated into the transparent vertical header through multi-parallel microchannel tubes in the bottom pass and exits through multi-parallel microchannel tubes in the top pass representing the flow in the heat pump mode of a reversible microchannel heat exchanger. Based on the visualization, the best distribution is when the momentum in the upper region is high enough to lift liquid to the top, while the momentum in the lower region is not too high to create semi-annular flow. An empirical function is derived to model refrigerant distribution by relating liquid takeoff ratio with inlet quality, vapour phase Reynolds number and Froude number in the header immediately upstream of the microchannel tube.

Original languageEnglish (US)
Title of host publication24th IIR International Congress of Refrigeration, ICR 2015
PublisherInternational Institute of Refrigeration
Pages1748-1755
Number of pages8
ISBN (Electronic)9782362150128
DOIs
StatePublished - 2015
Event24th IIR International Congress of Refrigeration, ICR 2015 - Yokohama, Japan
Duration: Aug 16 2015Aug 22 2015

Other

Other24th IIR International Congress of Refrigeration, ICR 2015
CountryJapan
CityYokohama
Period8/16/158/22/15

ASJC Scopus subject areas

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

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