Experimental and numerical studies on stack effect in a vertical shaft

Stack effect should be considered carefully while designing smoke control system for very tall buildings of height over 300 m. Buildings with a tall vertical shaft located in very cold countries would have very high stack pressure. In designing smoke management systems such as smoke exhaust and staircase pressurization system, stack effect was estimated by simple hydrostatic equations. As there are few experimental data on tall buildings supporting those equations, the authority is starting to challenge using those equations in estimating stack pressure. Hydrostatic equations would be justified by experimental scale modeling studies and numerical simulation with Computational Fluid Dynamics in this article. Stack effect was studied in a scale model shaft of size 0.05 m by 0.05 m and height 2.0 m. Air temperature inside the model was kept at different constant values above outdoor by wounding hot electric wires of power up to 600 kW. Vertical air temperature and pressure difference between indoor and outdoor air profiles inside and outside of the model at different heights were measured. The Computational Fluid Dynamics package, Fire Dynamics Simulator developed at the National Institute of Standards and Technology, U.S.A. was used for better understanding stack effect. Results were analyzed and compared with those estimated by simple hydrostatic models.