XXXXXXXXXXpdf
Question 1 (10)
Your consulting firm is requested to undertake a fire safety...

Question

XXXXXXXXXXpdf
Question 1 (10) 
Your consulting firm is requested to undertake a fire safety engineering assessment of a multi-
storey commercial building with a large atrium. The atrium connects multi-floors. A schematic 
layout of the building is given in Figure 1. One of the design solutions is to use a natural 
ventilation system for smoke control in the atrium. 
a) In your opinion, what will be the appropriate modelling tool for predicting 
smoke movement in the building and evaluating the performance of the smoke control 
system? Justify your decision (no more than 100 words). (5 Marks) 
b) Discuss the advantages and disadvantages of using your proposed modelling 
tool in comparison to other possible alternatives (

Dr Shweta · Accepted Answer

Ans 1 A) Smoke management system is an integral part of Fire Safety Engineering (FSE) because the major casualties during building fires occurred due to smoke. The appropriate modelling tool used here for smoke control, prediction of smoke movement and evaluation of smoke control system in the building is the large-eddy simulation CFD code based Fire Dynamics Simulator (FDS) model. This model is chosen because it is a field fire model with smoke analysis specifically structured for rectangular mesh as shown in figure 1. It is cost effective and versatile model for huge spacious buildings like shopping-centre, mega- complexes with easy computer simulation.
Ans 1 B) Atria are example of large spaces where conventional zone approaches like ASMET are not sufficiently effective. The suitable modelling tool for atrium is the field based-Fire Dynamics Simulator (FDS) modelling tool. Its advantages and disadvantages in comparison to other modelling tools are as follows:
1. Advantages-
· The FDS modelling tool is versatile and cost effective.
· It provides numerical simulation of fire-generated smoke movement in large complex space where conventional zone-model is not effective. And can covers huge spacious buildings like mega-complexes, convention centres, etc. efficiently. 
· It provides the transient development of the smoke profile, temperature distribution profile and velocity field.
· It provides high level of safety and can link outside building weather conditions and smoke and fire development.
· It provides effective strategy or controlling the smoke filling, gravity venting and smoke exhaust.
· Its tenability system approach provides complete protection to occupants with no exposure to smoke during evacuation in case of building fire.
2. Disadvantages-
The main disadvantage of this tool is that it is applicable only for the low-speed flow. It is not suitable for flow speeds approaching the speed of sound as in case of explosions, choke flow at nozzles, and detonations.
Ans 2a) The floor area mentioned in figure 1 is 30 m * 20 m = 600m2. The effective vent size should be 3.5% of maximum floor area so equal to 21m2 and the make-up air vent size should be 1.2 % of maximum floor area so equal to 7.2m2. 
2b) here we applied the zone fire model –the ASMET model to calculate the amount of smoke evolved the distribution pattern of smoke, dispersion of fire gases and temperature attained throughout the complex. This model consists of a set of equations and provides the analysis of smoke management systems for big spaces like atria.
2c) Smoke view diagram-Vent opening
2d) EXCEL graphics of the factors -  input heat release rate, output of smoke layer height, temperature, CO concentration and smoke extinction coefficient in the smoke layer as functions of time in the atrium is as follows: 
2 e) With the evolution of fire, the temperature, heat release and co concentration increases in the atrium.
Ans 3 A beam smoke detector is a device that utilizes a projected beam of light to detect smoke across large areas. It typically acts as a fire indicator of buildings.  The beam smoke detector consists of a transreciever unit that projects, monitors and transreciever a beam reflected across the protected area. The detector works on the principle of light obscuration.  Given that the activation transmittance of the detector is 0.65 it means 65% of incident light which is transmitted .

Solution

Answer To This Question Is Available To Download

Related Questions & Answers

Submit New Assignment