Effect of increased cabin recirculation airflow fraction on relative humidity, CO2 and TVOC

Victor Norrefeldt*, Florian Mayer, Britta Herbig, Ria Ströhlein, Pawel Wargocki, Fang Lei

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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In the CleanSky 2 ComAir study, subject tests were conducted in the Fraunhofer Flight Test Facility cabin mock-up. This mock-up consists of the front section of a former in-service A310 hosting up to 80 passengers. In 12 sessions the outdoor/recirculation airflow ratio was altered from today’s typically applied fractions to up to 88% recirculation fraction. This leads to increased relative humidity, carbon dioxide (CO2) and Total Volatile Organic Compounds (TVOC) levels in the cabin air, as the emissions by passengers become less diluted by outdoor, dry air. This paper describes the measured increase of relative humidity, CO2 and TVOC level in the cabin air for the different test conditions.

Original languageEnglish
Article number15
Issue number1
Pages (from-to)1-16
Publication statusPublished - 2021

Bibliographical note

Funding Information:
Funding: This study received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 820872-ComAir-H2020-CS2-CFP07-2017-02.


  • Adaptive ECS
  • Aircraft air quality
  • Subject testing


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