Periodical reverse flow and boiling fluctuations in a microchannel evaporator of an air-conditioning system

Hanfei Tuo, Pega Hrnjak

Research output: Contribution to journalArticlepeer-review

Abstract

This paper presents the phenomenon of periodic reverse flow and associated boiling fluctuation found in experiments with a parallel microchannel evaporator used in an R134a air conditioning system. A simultaneous flow visualizations and measurements confirmed the periodic flow reversal. It caused synchronized oscillations of the evaporator inlet pressure and the pressure drop. The magnitude and frequency of oscillations increased with heat flux. Three potential impacts of flow reversal on evaporator performance are identified: 1) moderate liquid maldistribution; 2) reduced heat transfer coefficient; 3) increased refrigerant side pressure drop. Finally, to mitigate impacts of periodic reverse flow, a solution is proposed: to vent and bypass backflow vapor accumulated in the inlet header.

Original languageEnglish (US)
Pages (from-to)1263-1275
Number of pages13
JournalInternational Journal of Refrigeration
Volume36
Issue number4
DOIs
StatePublished - Jun 2013

Keywords

  • Boiling fluctuation
  • Flow visualization
  • Microchannel evaporator
  • Periodic reverse flow

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering

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