## THERMAL SCIENCE

International Scientific Journal

### Thermal Science - Online First

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

**ABSTRACT**

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.

**KEYWORDS**

PAPER SUBMITTED: 2020-01-16

PAPER REVISED: 2020-08-31

PAPER ACCEPTED: 2020-09-22

PUBLISHED ONLINE: 2020-10-10

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