Sustainable smoke extraction system for atrium : a numerical study

Abstract

Smoke extraction systems, either static with natural ventilation, or dynamic with mechanical ventilation are required to keep smoke layer at high levels in many tall atria. It is observed that a design fire with high heat release rate (HRR) is commonly used for designing natural vents, but a low HRR is used for mechanical ventilation system. This will not produce a sustainable environment. There are no internationally agreed on design guides to determine the HRR in the design fire for different extraction systems and scenarios. This issue will be studied using a Computational Fluid Dynamics (CFD)-based software, the Fire Dynamics Simulator (FDS) version 6.7.1. Simulations on natural smoke filling, static and dynamic smoke extractions were carried out in a big example atrium. CFD-FDS predictions were compared with previous full-scale burning tests. Results confirmed that static smoke extraction is a good option for big fires, and a dynamic system is best for small fires. A sustainable new hybrid design combining the advantages of static and dynamic systems is proposed, which could result in a lower smoke temperature and higher smoke layer interface height, indicating a better extraction design.