Analysis of cold air recirculation in the evaporators of large‐scale air‐source heat pumps using CFD simulations

Brice Rogié, Jonas Kjær Jensen, Svenn Ole Kjøller Hansen, Wiebke Brix Markussen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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The present study investigates cold air recirculation in the evaporators of large‐scale air-source heat pumps. A case study considered a 5 MW air‐source heat pump producing heat for district heating. The heat pump comprises 20 horizontal evaporators, where each evaporator is equipped with eight fans. The evaporators were implemented in a CFD model, where the influence of the outdoor wind direction on the recirculation was investigated. Firstly, the air recirculation was analysed with no surrounding obstacles. Secondly, the surrounding building and the real ground topology was included in the CFD model, to analyse their influence on the air recirculation. The results show that recirculation occurs for all wind directions, due to the turbulent behaviour of the flow around the evaporators. The results also show that the presence of a building intensifies the recirculation when it is placed directly upstream of the evaporators due to the presence of vortices in the wake of the building. On the other hand, a ground depression helps to reduce the recirculation by having additional energy dissipation due to the sudden change in the ground direction.

Original languageEnglish
Article number186
Issue number4
Number of pages25
Publication statusPublished - 2020

Bibliographical note

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (


  • Air recirculation
  • CFD
  • Large‐scale air‐source heat pump

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