Noise reduction of refrigerant two-phase flow using flow conditioners near the electric expansion valve
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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.
KeywordsNoise reduction Flow conditioner Refrigerant two-phase flow Electric expansion valve
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This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Science, ICT, and Future Planning) (No. 2016R1A2B3009541), and the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resources from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20184010201710).
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