NUMERICAL INVESTIGATIONS OF THE INDOOR THERMAL ENVIRONMENT IN ATRIA AND OF THE BUOYANCY- DRIVEN VENTILATION IN A SIMPLE ATRIUM BUILDING
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In recent years Computational Fluid Dynamics (CFD) has been extensively used in the study of the indoor environment and the thermal comfort conditions for the design of modern buildings, however, there remains the need to thoroughly evaluate the accuracy of the results given by CFD methods. In the present work, numerical investigations of the indoor thermal environment in the atria of two existing buildings and in a simple three-storey atrium building design have been undertaken using CFD techniques. The initial work involved the evaluation of various turbulence models and a radiation model used in CFD simulations for the prediction of the thermal environment in atria of different geometrical configurations in two buildings for which experimental data is available. The airflow patterns and temperature distributions were determined, under both forced and hybrid ventilation conditions and thermal comfort conditions were evaluated. The numerical predictions were compared with the available experimental measurements and, in general, good agreement was obtained between the numerical and experimental results. After the evaluation of the adequacy of available turbulence models and the validation of the accuracy of the CFD model used, a simple full-scale three-storey atrium building was modeled to explore the potential of using buoyancy-driven natural ventilation. The validated CFD model was used to determine the ventilation flow rates, airflow patterns, and temperature distributions in the building. The dynamic effect of the thermal mass of the external walls on the performance of the building was also investigated using transient CFD simulations. Atria with various geometrical configurations were studied in order to investigate the effect of atrium design changes on the air flow and temperature distributions in the simple atrium building considered. A parametric study was carried out to assess the sensitivity of the ventilation performance to the change in various geometric and solar parameters. On the basis of this parametric study, a few changes were carried out in the design of the building to examine their effect on ventilation performance. Finally, the use of night ventilation in the atrium building was explored and it was found that night ventilation can be increased by using hot water circulation in the chimney walls.