An experimental study on performance during reverse cycle defrosting of an air source heat pump with a horizontal threecircuit outdoor coil

Song Mengjie, Xu Xiangguo, Shiming Deng, Mao Ning

Research output: Journal article publicationConference articleAcademic researchpeer-review

10 Citations (Scopus)


When the surface temperature of the outdoor coil in an air source heat pump (ASHP) unit is below both the air dew point and freezing point of water, frost can be formed and accumulated over the surface of the outdoor coil, which is usually of multi-circuit structure in order to minimize its refrigerant pressure loss and enhance the heat transfer between refrigerant and ambient air. However, frosting adversely affects the operational performance and hence the energy efficiency of the ASHP unit, therefore periodic defrosting is necessary. Currently, the most widely standard defrosting method used for ASHP units is reverse cycle defrosting. A previous related study has suggested that during reverse cycle defrosting, downwards flowing of melted frost due to gravity over a vertical multi-circuit outdoor coil in an ASHP unit could deteriorate defrosting performance, by using more energy for defrosting and prolonging a defrosting process. If however an outdoor coil can be horizontally installed, the flow path for melted frost over coil surface can be shortened, and a better defrosting performance expected. In this paper, therefore, an experimental study on performance during reverse cycle defrosting of an ASHP unit having a horizontal three-circuit outdoor coil has been carried out. Firstly, a detailed description of the ASHP unit is presented. This is followed by reporting the experimental results. Finally, a comparative and quantitative analysis is given.
Original languageEnglish
Pages (from-to)92-95
Number of pages4
JournalEnergy Procedia
Publication statusPublished - 1 Jan 2014
Event6th International Conference on Applied Energy, ICAE 2014 - National Taiwan University of Science and Technology, Taipei, Taiwan
Duration: 30 May 20142 Jun 2014


  • Air source heat pump
  • Defrosting
  • Experiment
  • Horizontal
  • Melted frost
  • Multi-circuit

ASJC Scopus subject areas

  • Energy(all)

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