Evaluation of Atrium Smoke Exhaust Make-Up Air Velocity.

The rapid smoke spread through an atrium in case of fire is a major concern. Although natural ventilation can be used to keep the smoke layer at high levels, in some cases, such a system may not be effective allowing smoke to reach low levels in the atrium and it is not frequently used in North America, where mechanical ventilation is the preferred atrium smoke management system used. Guidelines for the design of mechanical smoke exhaust systems require that the maximum velocity of the make-up air velocity be restricted to 1 m/s, a criterion that for some buildings causes great difficulties to designers. In this study, a CFD model was used to evaluate this criterion for make-up air velocity and to determine if this limit is appropriate. The study considered different fire sizes in various size atria equipped with smoke exhaust systems. The results of the analysis indicate that, for some cases, increasing the velocity limit may have a negative impact on the fire plume and the hot layer height. [ABSTRACT FROM AUTHOR]