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Numerical simulation of the CO2-diffusion effect on low turbulent mixed convection in a ventilated room heated by the bottom

A double-diffusive mixed convection within low-turbulent regime in a ventilated cavities filled with an air-CO2 mixture and heated from below has been numerically investigated. The lower wall was sustained at a uniform temperature and CO2-concentration. The vertical and upper walls were kept at external temperature and CO2-concentration. To analyze the behavior of flow, the ventilation effectiveness for temperature distribution and removal of CO2-contaminant, four configurations were dealt. These differ from each other by the location of the mixture inlet and outlet gaps. Likewise, three CO2-concentrations were considered (103, 2x103 and 3x103 ppm) to investigate the influence of the CO2-diffusion on the ventilation effectiveness. The numerical simulations were performed by considering closed Reynolds averaged-Navier-Stokes (RANS) equations using the Re-Normalization Group k-ε model. The governing equations' set was then solved using the finite volume method, in which the pressure-velocity coupling was handled using the SIMPLEC algorithm. Validation of the numerical model was achieved by comparing our results with available experimental data. The obtained results indicate that the CO2-diffusion effect on the air movement and the ventilation effectiveness for temperature distribution can be neglected in the present study. However, the CO2-diffusion remains a key parameter in terms of indoor air quality index. Also, it was found that one of the studied configurations provides a better ventilation effectiveness to remove heat and CO2-contaminant, and insures a homogeneous temperature and CO2-concentration in the occupied zone. The three other configurations maintain an acceptable level of heat and can be used in temperate climate to ensure good indoor air quality.
PAPER REVISED: 2020-08-31
PAPER ACCEPTED: 2020-09-22
  1. Deng, Q.-H., et al., Fluid, heat and contaminant transport structures of laminar double-diffusive mixed convection in a two-dimensional ventilated enclosure, International Journal of Heat and Mass Transfer, 47 (2004), 24, pp. 5257-5269.
  2. Marchand, C., et al., Aldehyde measurements in indoor environments in Strasbourg (France), Atmospheric Environment, 40 (2006), 7, pp. 1336-1345.
  3. Kabir, E., et al., Indoor air quality assessment in child care and medical facilities in Korea, Environmental Monitoring and Assessment, 184 (2012), 10, pp. 6395-6409.
  4. Xamán, J., et al., Effect of a contaminant source (CO2) on the air quality in a ventilated room, Energy, 36 (2011), 5, pp. 3302-3318.
  5. Serrano-Arellano, J., et al., Optimum ventilation based on the ventilation effectiveness for temperature and CO2 distribution in ventilated cavities, International Journal of Heat and Mass Transfer, 62 (2013), pp. 9-21.
  6. Liu, D., et al., Turbulent transport of airborne pollutants in a residential room with a novel air conditioning unit, International Journal of Refrigeration, 35 (2012), 5, pp. 1455-1472.
  7. Cao, S.-J., Meyers, J., On the construction and use of linear low-dimensional ventilation models, Indoor Air, 22 (2012), 5, pp. 427-441.
  8. Cao, S.-J., Meyers, J., Influence of turbulent boundary conditions on RANS simulations of pollutant dispersion in mechanically ventilated enclosures with transitional slot Reynolds number, Building and Environment, 59 (2013), pp. 397-407.
  9. Deng, H.-Y., et al., Influence of air change rates on indoor CO2 stratification in terms of Richardson number and vorticity, Building and Environment, 129 (2018), pp. 74-84.
  10. Saha, S., et al., Double diffusive mixed convection heat transfer inside a vented square cavity, Chemical Engineering Research Bulletin, 13 (2009), 1, pp. 17-24.
  11. Abidi A., et al., Effect of heat and mass transfer through diffusive walls on three-dimensional double-diffusive natural convection, Numerical Heat Transfer, Part A, 53 (2008), pp. 1357-1376.
  12. Abidi A., et al., Effect of radiative heat transfer on three-dimensional double diffusive natural convection, Numerical Heat Transfer, Part A, 60 (2011), pp. 785-809.
  13. Ahmed K .H., et al. Three-dimensional unsteady natural convection and entropy generation in an inclined cubical trapezoidal cavity with an isothermal bottom wall, Alexandria Engineering Journal, 55 (2016), pp. 741-755.
  14. Krajčík M., et al., Air distribution and ventilation effectiveness in an occupied room heated by warm air, Energy and Buildings, 55 (2012), pp. 94-101.
  15. Rodríguez-Muñoz, N. A., et al., Numerical study of heat transfer by convection and thermal radiation in a ventilated room with human heat generation and CO2 production, Latin American Applied Research, 43 (2013), pp. 353-361.
  16. Serrano-Arellano, J., et al., Indoor air quality analysis based on the ventilation effectiveness for CO2 contaminant removal in ventilated cavities, Revista Mexicana Física, 60 (2014), 4, pp. 309-317.
  17. Serrano-Arellano, J., et al., Numerical investigation of transient heat and mass transfer by natural convection in a ventilated cavity: Outlet air gap located close to heat source, International Journal of Heat and Mass Transfer, 76 (2014), pp. 268-278.
  18. Blay, D., et al., Confined turbulent mixed convection in the presence of a horizontal buoyant wall jet, ASME Fundamentals of Mixed Convection HTD, 213 (1992), pp. 65-72.
  19. Poling, B. E., et al., The properties of gases and liquids, 5th Ed. McGraw-Hill, NewYork, USA, 2001.
  20. Koufi, L., et al., Numerical investigation of turbulent double-diffusive mixed convection in a slot ventilated enclosure with supply air flow ports, 23ème Congrès Français de Mécanique, 2017, Lille, France.
  21. Koufi, L., et al., Numerical investigation of turbulent mixed convection in an open cavity: Effect of inlet and outlet openings, International Journal of Thermal Sciences, 116 (2017), pp. 103-117.
  22. Koufi, L., et al, Double-diffusive natural convection in a mixture-filled cavity with walls' opposite temperatures and concentrations, Heat Transfer Engineering, 40 (2018), 15, pp. 1-18.
  23. Koufi, L., et al., A numerical study of indoor air quality in a ventilated room using different strategies of ventilation, Mechanics and Industry, 18 (2017), 2, pp. 1-9.
  24. Younsi, Z., et al., Numerical study of the effects of ventilated cavities outlet location on thermal comfort and air quality, Int. J. of Numerical for Methods for Heat and Fluid Flow, 29 (2019), 11, pp. 4462-4483.
  25. Ampofo, F., Karayiannis, T. G., Experimental benchmark data for turbulent natural convection in an air-filled square cavity, International Journal of Heat and Mass Transfer, 46 (2003), 19, pp. 3551-3572.
  26. Cao, G., et al., A review of the performance of different ventilation and airflow distribution systems in buildings, Building and Environment, 73 (2014), pp. 171-186.
  27. Awbi, H. B., Ventilation of buildings, 2nd ed. Routledge, New York, USA, 2003.