Numerical studies on engineered smoke control for large flat space with low ceiling

• Main Author: Ng, Jasmine Shiou Yuan
• Other Authors: Wan Man Pun
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/141730
• Institution: Nanyang Technological University

In Singapore, most of the office buildings are high rise and clustered around the downtown area. Where are fire related incidents, deaths are caused when occupants inhaled smoke that contain toxic gases which causes oxygen deprivation. Amongst the toxic gases produced, Carbon Monoxide (CO) poisoning is the leading factor for the cause of death in fire incidents. For occupants in offices with low ceiling and poor ventilation, this poses a bigger threat for them. Moreover, the smoke management in these spaces often have the smoke reservoir depth breaching the minimum clear layer requirement and causing a great challenge when designing the systems. Therefore, this project aims to design an Engineered Smoke Control (ESC) system in compliance with the minimum requirement to satisfy the tenability criteria as specified in the Singapore Fire Safety Engineering Guidelines (SFSEG) 2015 produced by SCDF. Realising smoke movement is critical for fast and safe evacuation of occupants to be successful. Thus to do so, this requires calculations of smoke movement in a typical large space office setting. It is also important to find possible designs of smoke containments for better evacuation and also to define large space with low ceiling height. Using Fire Dynamics Simulator (FDS) to do numerical assessments on different model layouts together with PyroSim and SmokeView to pre – process the simulations and post – process the simulation results. Hence this project conducts multiple optimisation studies on the ESC system to improve the effectiveness and efficiency of the system. Based on the findings, it was found that with the addition of smoke barriers to the design, smoke was distributed evenly and kept under control in a zonal method. On top of that, defining the large space and finding the minimum ceiling height of the space was important as the height is related to the smoke reservoir depth which breaches the tenability criteria. It was also observed that the extraction vents configuration did not impact much on extraction of smoke and the time taken to reach certain parameters that was set. To design the system to not only be efficient and at the same time, energy – saving, smoke detectors were installed in the space as part of automated smoke detection. In addition to that, the minimum volumetric flow rate of the ESC system was also tested to see the most efficient flow rate that will still provide a safe egress time for occupants to exit safely while reducing the capacity of extraction vents and the reduction in extraction duct sizing. Lastly, from the simulation findings, the 4 smoke barriers with the barrier height of 2.5m showed the most advantageous results for safe egress time with simulation obtained flow rate value for the required volumetric exhaust flow rate to have the reduction of extraction vents and hence having a reduced size for the required extraction ducts, saving initial costs and space requirements needed.