Effect of Buoyancy on Room Air Flow

Thermal comfort and ventilation needs of spaces are met by supplying “conditioned” air, which is a blend of outdoor and recirculated air that has been filtered, heated or cooled, and sometimes humidified or dehumidified. Comfort conditions in air-conditioned rooms require that temperature in the occupied zone should not vary by more than 1°C and velocity, every where in the room, should be less than 0.15 m/s so that occupants do not feel draft. Recent developments in providing effective insulation and making leak tight building shell have considerably reduced the cooling load requirements and the supply airflow rates. Obtaining uniform temperature distribution with reduced air volume flow rates requires careful design of air distribution system. This study aims to find velocity and temperature distribution in the room towards this end. Coanda effect, effect of buoyancy and wall boundary layers has been observed in this investigation. The Coanda effect is observed in all the cases of laminar flow. Cold fluid enters in the room near the ceiling, the flow attaches with the ceiling, comes down along the right wall and goes out from outlet.