A Short Note on Using a Time Constant in Specifying Smoke Filling Time in an Atrium Under an Unsteady Fire

1995 ◽  
Vol 13 (6) ◽  
pp. 434-444 ◽  
Author(s):  
W.K. Chow
Keyword(s):  
Control Systems ◽  
Time Constant ◽  
Short Note ◽  
Zone Model ◽  
Smoke Control ◽  
Fire Zone ◽  
Filling Time ◽  
Version 2.0 ◽  
Smoke Filling

A time constant derived from a t-squared fire with the geometry of an atrium is proposed to specify the smoke filling time. The smoke filling pro cesses in 27 atria with volume varying from 2,500 to 35,000 m3 were simulated by the fire zone model CFAST version 2.0. The atria are located adjacent to a "fire" shop at a lower level. Correlation relationships between the smoke filling time and the time constant are derived. Further, performance of smoke control systems in the atria are evaluated.

Use of a Time Constant for Designing a Smoke Control System in Car Parks

1995 ◽  
Vol 13 (5) ◽  
pp. 357-377 ◽  
Author(s):  
W.K. Chow
Keyword(s):  
Time Constant ◽  
Extraction System ◽  
Zone Model ◽  
Smoke Control ◽  
Empirical Expression ◽  
Fire Environment ◽  
Filling Time ◽  
Version 2.0 ◽  
Smoke Control System ◽  
Space Volume

The fire environment in thirty-six car parks of volumes varying from 2,000 m3 to 50,000 m3, ceiling heights of 3 m, 4 m and 5 m are simulated using the fire zone model, CFAST version 2.0 developed at the Building and Fire Research Laboratory, NIST in U.S.A. The concept of using the space volume as a criterion to determine the requirement of smoke extraction system is reviewed. The concept of time constant in an atrium hall is proposed to be used in car parks and underground spaces. The empirical expression fitted by experimental data appearing in NFPA-92B is applied to calculate the time con stant. This is then correlated with the smoke filling time for those thirty-six car parks with and without natural horizontal ceiling vents. Design of the smoke extraction system for underground spaces is also studied.

Application of the Zone Model FIRST on the Development of Smoke Layer and Evaluation of Smoke Extraction Design for Atria in Hong Kong

1993 ◽  
Vol 11 (4) ◽  
pp. 329-349 ◽  
Author(s):  
W.K. Chow ◽  
W.K. Wong
Keyword(s):  
Hong Kong ◽  
Time Constant ◽  
Research Laboratory ◽  
Fire Research ◽  
Extraction System ◽  
Zone Model ◽  
Geometrical Configuration ◽  
Design Fire ◽  
Smoke Layer ◽  
Smoke Filling

Whether a smoke extraction system has to be installed for an atrium building in Hong Kong is determined by its volume. This article reports an evaluation of this regulation using the zone model FIRST developed at the Building and Fire Research Laboratory, NIST, U.S.A. A survey of the geometri cal configurations of the local atria is made. The general shapes of the atria are classified into three types: 1, 2 and 3, with types 2 and 3 further divided into three sub-types: A, B and C. Smoke filling in those atria is simulated by the model FIRST with the volumes of the atrium space varied from 2500 m3 to 35,000 m 3. It is illustrated that specifying only the volume of the atrium space is not good enough to determine whether a smoke extraction system has to be installed. The geometrical configuration is recommended to be included as well. A time constant is defined for the atrium with a certain design fire.

Simulation of Smoke Movement in a Loop Corridor under Mechanical Exhaust with Compound Model

2013 ◽  
Vol 475-476 ◽  
pp. 1459-1462
Author(s):  
Wei Shi ◽  
Fu Sheng Gao
Keyword(s):  
Field Model ◽  
Unit Area ◽  
Zone Model ◽  
Smoke Control ◽  
Smoke Movement ◽  
High Rise ◽  
Compound Model ◽  
Ceiling Height ◽  
Dynamic Simulator ◽  
Fire Dynamic Simulator

The mechanical smoke exhaust is as acknowledged as an effective smoke control manner by making use of some necessary exhaust facilities, also with more stability than natural exhaust. In this paper, the field model FDS (Fire Dynamic Simulator) with a combination of zone model CFAST (Consolidate Fire and Smoke Transport) were used to simulate the mechanical smoke exhaust in a loop corridor of the fire floor in a high-rise hotel, for the propose of evaluate fire safety of mechanical smoke exhaust. The mainly discussion was about the height of layer interface with the ceiling height changed, also with different smoke exhaust volume. The conclusions were obtained that, when two exhaust vents were set symmetrically in the loop corridor, the volume of smoke exhaust per unit area with 60m3/h according to regulations, always could ensure safety of smoke exhaust. The smoke exhausted worse within the corridor when ceiling height reduced. It was recommended that the ceiling lowest height limit should be provides in correlative regulation.

Numerical analysis of combined buoyancy-induced and pressure-driven smoke flow in complex vertical shafts during building fires

2016 ◽  
Vol 26 (6) ◽  
pp. 1684-1698 ◽  
Author(s):  
Yanqiu Chen ◽  
Xiaodong Zhou ◽  
Taolin Zhang ◽  
Zhijian Fu ◽  
Yuqi Hu ◽  
...  
Keyword(s):  
Heat Source ◽  
Control Systems ◽  
Systems Design ◽  
Research Approach ◽  
Smoke Control ◽  
Building Fires ◽  
Content Type ◽  
Smoke Flow ◽  
Significant Difference ◽  
Pressure Driven

Purpose – The purpose of this paper is to study the behavior of smoke flow in building fires and optimize the design of smoke control systems. Design/methodology/approach – A total of 435 3-D fire simulations were conducted through NIST fire dynamics simulator to analyze thermal behavior of combined buoyancy-induced and pressure-driven smoke flow in complex vertical shafts, under consideration of influence of heat release rate (HRR) and locations of heat sources. This influence was evaluated through neutral pressure plane (NPP), which is a critical plane depicting the flow velocity distributions. Hot smoke flows out of shafts beyond the NPP and cold air flows into shafts below the NPP. Findings – Numerical simulation results show that HRR of heat source has little influence on NPP, while location of heat source can make a significant difference to NPP, particularly in cases of multi-heat source. Identifying the location of NPP helps to develop a more effective way to control the smoke with less energy consumption. Through putting an emphasis on smoke exhausting beyond the NPP and air supplying below the NPP, the smoke control systems can make the best use of energy. Research limitations/implications – Because of the chosen research approach, the research results may need to be tested by further experiments. Practical implications – The paper includes implications for the optimization of smoke control systems design in buildings. Originality/value – This paper fulfills an identified need to research the behavior of hot smoke in building fires and optimize the design of smoke control systems.

Simulation and Analyzing of Mechanical Smoke Exhaust in a High-Rise Building

2013 ◽  
Vol 726-731 ◽  
pp. 3596-3599
Author(s):  
Wei Shi ◽  
Fu Sheng Gao
Keyword(s):  
Fire Safety ◽  
Field Model ◽  
Unit Area ◽  
Zone Model ◽  
Smoke Control ◽  
Control Manner ◽  
High Rise ◽  
High Rise Building

The mechanical smoke exhaust is as acknowledged as an effective smoke control manner by making use of some necessary exhaust facilities. In this paper, a field model with a combination of a zone model were used to simulate the mechanical smoke exhaust in a loop corridor of the fire floor in a high-rise hotel, for the propose of evaluate fire safety of mechanical smoke exhaust. There were several factors are under discussion, as the arrangement of smoke vents, quantity of smoke vents, the volume of smoke exhaust, the position of the smoke vents and height of ceiling indoor, et al. The conclusions were obtained as followed. When two exhaust vents were set symmetrically in the loop corridor, one of which was located nearby the fire room, the smoke exhausted better. The volume of smoke exhaust per unit area with 60m3/h according to regulations, always could ensure safety of smoke exhaust.

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