Experimental analysis of the air-handling unit capable of modulation control based on CO2 content in the classroom


Heat Transfer Research, vol.51, no.17, pp.1517-1529, 2020 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 51 Issue: 17
  • Publication Date: 2020
  • Doi Number: 10.1615/heattransres.2020035682
  • Journal Name: Heat Transfer Research
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Communication Abstracts, Compendex, INSPEC, Metadex, Civil Engineering Abstracts
  • Page Numbers: pp.1517-1529
  • Keywords: Air-conditioning unit, Carbon dioxide, Energy conservation, Plate heat recovery
  • Hacettepe University Affiliated: Yes


© 2020 by Begell House, Inc.People spend most of their lives indoors today. Therefore, the importance of indoor air quality increases with each passing day, particularly, when the current quality of life expectations is taken into consideration. One of the factors affecting indoor air quality is the amount of CO2 in the air. In this study, by using an air-handling unit (AHU) with plate heat recovery, the correlation of CO2 concentration variations based on the number of students present in a classroom of the university was evaluated. Also, alterations in the energy consumption, depending on the variable mixing unit ratios of AHU, were monitored. In the measurements, the measured CO2 concentration was at its highest level (1350 ppm) while the AHU was not active and 70 students were in the classroom. The CO2 concentration was 1087 ppm when 50 students were in the classroom. When the AHU was operated with 100% fresh air, the CO2 concentrations were 765 ppm and 682 ppm in the experiments with 70 and 50 students, respectively. Besides, when the AHU was operated with 60% fresh air, the measured CO2 concentration in the classroom was 889 ppm for 70 students, and 851 ppm for 50 students. In the experiments, the lowest energy consumption was calculated as 13.1 kW/h when there was no student in the classroom, and the AHU was operated with 60% fresh air. In the experiments, the highest energy consumption was calculated as 15.8 kW/h when there were 70 students in the classroom, and the AHU was operated with 100% fresh air.