Effect of airflow rate on CO2 concentration in downflow indoor ventilation
We perform direct numerical simulations to study the effect of increasing airflow rate on CO2 concentration in downflow and displacement ventilation in a room with one occupant. Often, CO2 concentration is used as a proxy for the concentration of bio-aerosols of respiratory droplets, and therefore,...
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| Format: | Article |
| Language: | English |
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Elsevier
2024-06-01
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| Series: | Indoor Environments |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2950362024000092 |
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| author | Guru Sreevanshu Yerragolam Christopher J. Howland Rui Yang Richard J.A.M. Stevens Roberto Verzicco Detlef Lohse |
| author_facet | Guru Sreevanshu Yerragolam Christopher J. Howland Rui Yang Richard J.A.M. Stevens Roberto Verzicco Detlef Lohse |
| author_sort | Guru Sreevanshu Yerragolam |
| collection | DOAJ |
| description | We perform direct numerical simulations to study the effect of increasing airflow rate on CO2 concentration in downflow and displacement ventilation in a room with one occupant. Often, CO2 concentration is used as a proxy for the concentration of bio-aerosols of respiratory droplets, and therefore, tracking the CO2 concentration in ventilation strategies can be useful to understand and quantify the risk of spread of communicable respiratory illnesses. At low to moderate airflow rates, the flow in the downflow setup is not mixed, but stratified. The CO2 concentration in the upper and lower layers is determined by the strength of the thermal plume originating from the occupant. We provide a simple theoretical model to predict the height of the stratified interface, the volumetric flux of the ascending plume, and the CO2 concentration in the lower and upper layers. At very high airflow rates, the flow is well-mixed and the average CO2 concentration in the room can be predicted with the mixing ventilation assumption. We demonstrate that at low to moderate airflow rates, displacement ventilation more effectively maintains lower CO2 concentrations in the lower layer compared to downflow ventilation. |
| format | Article |
| id | doaj-art-242138f21c77413fb0f68f30263aaa22 |
| institution | DOAJ |
| issn | 2950-3620 |
| language | English |
| publishDate | 2024-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Indoor Environments |
| spelling | doaj-art-242138f21c77413fb0f68f30263aaa222025-08-20T02:50:14ZengElsevierIndoor Environments2950-36202024-06-011210001210.1016/j.indenv.2024.100012Effect of airflow rate on CO2 concentration in downflow indoor ventilationGuru Sreevanshu Yerragolam0Christopher J. Howland1Rui Yang2Richard J.A.M. Stevens3Roberto Verzicco4Detlef Lohse5Physics of Fluids Group, Max Planck Center for Complex Fluid Dynamics, J. M. Burgers Center for Fluid Dynamics, P.O. Box 217, Enschede 7500AE, the Netherlands; Corresponding author.Physics of Fluids Group, Max Planck Center for Complex Fluid Dynamics, J. M. Burgers Center for Fluid Dynamics, P.O. Box 217, Enschede 7500AE, the NetherlandsPhysics of Fluids Group, Max Planck Center for Complex Fluid Dynamics, J. M. Burgers Center for Fluid Dynamics, P.O. Box 217, Enschede 7500AE, the NetherlandsPhysics of Fluids Group, Max Planck Center for Complex Fluid Dynamics, J. M. Burgers Center for Fluid Dynamics, P.O. Box 217, Enschede 7500AE, the NetherlandsDipartimento di Ingegneria Industriale, Via del Politecnico 1, Roma 00133, Italy; Gran Sasso Science Institute, Viale F. Crispi, L’Aquila 7 67100, ItalyPhysics of Fluids Group, Max Planck Center for Complex Fluid Dynamics, J. M. Burgers Center for Fluid Dynamics, P.O. Box 217, Enschede 7500AE, the Netherlands; Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, Göttingen 37077, GermanyWe perform direct numerical simulations to study the effect of increasing airflow rate on CO2 concentration in downflow and displacement ventilation in a room with one occupant. Often, CO2 concentration is used as a proxy for the concentration of bio-aerosols of respiratory droplets, and therefore, tracking the CO2 concentration in ventilation strategies can be useful to understand and quantify the risk of spread of communicable respiratory illnesses. At low to moderate airflow rates, the flow in the downflow setup is not mixed, but stratified. The CO2 concentration in the upper and lower layers is determined by the strength of the thermal plume originating from the occupant. We provide a simple theoretical model to predict the height of the stratified interface, the volumetric flux of the ascending plume, and the CO2 concentration in the lower and upper layers. At very high airflow rates, the flow is well-mixed and the average CO2 concentration in the room can be predicted with the mixing ventilation assumption. We demonstrate that at low to moderate airflow rates, displacement ventilation more effectively maintains lower CO2 concentrations in the lower layer compared to downflow ventilation.http://www.sciencedirect.com/science/article/pii/S2950362024000092VentilationTransportThermal convectionTurbulenceDirect numerical simulations |
| spellingShingle | Guru Sreevanshu Yerragolam Christopher J. Howland Rui Yang Richard J.A.M. Stevens Roberto Verzicco Detlef Lohse Effect of airflow rate on CO2 concentration in downflow indoor ventilation Indoor Environments Ventilation Transport Thermal convection Turbulence Direct numerical simulations |
| title | Effect of airflow rate on CO2 concentration in downflow indoor ventilation |
| title_full | Effect of airflow rate on CO2 concentration in downflow indoor ventilation |
| title_fullStr | Effect of airflow rate on CO2 concentration in downflow indoor ventilation |
| title_full_unstemmed | Effect of airflow rate on CO2 concentration in downflow indoor ventilation |
| title_short | Effect of airflow rate on CO2 concentration in downflow indoor ventilation |
| title_sort | effect of airflow rate on co2 concentration in downflow indoor ventilation |
| topic | Ventilation Transport Thermal convection Turbulence Direct numerical simulations |
| url | http://www.sciencedirect.com/science/article/pii/S2950362024000092 |
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