An experimental study on the effects of downwards flowing of melted frost over a vertical multi-circuit outdoor coil in an air source heat pump on defrosting performance during reverse cycle defrosting

Mengjie Song, Shiming Deng, Dongmei Pan, Ning Mao

Research output: Journal article publicationJournal articleAcademic researchpeer-review

44 Citations (Scopus)


A previous related study has indicated that for an air source heat pump (ASHP) unit having a vertically installed multi-circuit outdoor coil, during reverse cycle defrosting, downwards flowing of melted frost over the outdoor coil surface could affect the defrosting performance, without however giving a detailed quantitative analysis. Therefore an experimental study has been carried out and the study results are reported in this paper. Firstly, a detailed description of a specially built experimental ASHP unit having a vertical multi-circuit outdoor coil is presented. This is followed by reporting the experimental results. Finally, a detailed quantitative analysis is presented. The experimental results and the corresponding analysis demonstrated that allowing downwards flowing of the melted frost over a vertical multi-circuit outdoor coil would result in a longer defrosting duration and more energy consumption. The study results also suggested that the use of water collecting trays can help mitigate these negative impacts on defrosting performance.
Original languageEnglish
Pages (from-to)258-265
Number of pages8
JournalApplied Thermal Engineering
Issue number1-2
Publication statusPublished - 1 Jun 2014


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

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

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