Noise reduction of refrigerant two-phase flow using flow conditioners near the electric expansion valve

Gangjune Kim, Simon Song

Research output: Contribution to journalArticle


Two-phase flow, particularly generated in an expansion device, is a primary cause of refrigerant-induced noise in an air-conditioning system. The indoor unit (IDU) of a multi-split air source heat pump (ASHP) for both heating and cooling must include an electric expansion valve (EEV); therefore, consumers have perceived the increased noise. To reduce this noise, we experimentally investigated the two-phase flow and consequent noise by applying a honeycomb and porous metal as a flow conditioner to the EEV in the IDU of a multi-split ASHP. Flow conditioning near the EEV with the honeycomb and porous metal made the two-phase flow steadier and more uniform, leading to reduced noise and frequency variation for the three heat operation modes of a multi-split ASHP. The noise reduction was also verified in the transient operating modes of a real IDU.

Original languageEnglish
Pages (from-to)719-725
Number of pages7
JournalJournal of Mechanical Science and Technology
Issue number2
Publication statusPublished - 2020 Feb 1



  • Electric expansion valve
  • Flow conditioner
  • Noise reduction
  • Refrigerant two-phase flow

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