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A Dynamic Model for Microchannel Heat Exchanger under Frost Conditions.

Number: No 110

Author(s) : LING J., WANG L., DHUMANE R., AUTE V.

Summary

Heat pump manufacturers gradually adopt microchannel heat exchangers (MCHX) as the outdoor coils due to the compactness and lower cost. The relatively small hydraulic diameter of MCHX also enhances the heat transfer compared to traditional tube and fin coils. However, such benefits may turn to a challenge when heat pumps operate under the frost condition. Air flow is easily blocked when frost builds up in the smaller flow channels formed by the fins and microchannel tubes. To study the MCHX performance under frost condition, we developed a Modelica-based dynamic model that accounts for the performance degradation under frost conditions. The MCHX is modeled using the finite volume method and the sensible and latent heat transfer between refrigerant and moist air is solved using both heat and mass conservation equations. Regarding the frost accumulation, the model considers both the frost densification and thickness growth which will reduce the conductivity of the tube surface and the minimum free flow area, leading to poor air-side heat transfer. The model can also be applied on a heat pump system along with other in-house developed Modelica component models to assist the understanding of heat pump COP degradation during frost.

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Pages: 12 p.

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Details

  • Original title: A Dynamic Model for Microchannel Heat Exchanger under Frost Conditions.
  • Record ID : 30029988
  • Languages: English
  • Subject: Technology
  • Source: 13th IEA Heat Pump Conference 2021: Heat Pumps – Mission for the Green World. Conference proceedings [full papers]
  • Publication date: 2021/08/31

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