(Q1) List and explain the tenability criteria that is commonly used in the
computational fluid dynamic (CFD) models by fire engineering design
approach for the ASET study in accordance with the Hong Kong FS
Code (Code of Practice for Fire Safety in Building 2011). Please also try
to explain the impacts of the fire on the human body on the basis of the
criteria you listed above.
(Q2) A compartment with the following data is subjected to a fire. The
compartment located in remote area is designed as office usage. The
following information is given:
Automatic smoke alarm is provided;
No independent water supplies are provided;
No firefighting devices are provided;
The office is made of concrete, ρ=2500kg/m3
; cp=980J/kgK;
k=1.5W/mK;
There are two ventilation openings on the walls. The dimensions
(breadth x height) are 3.6m x 1.5m for Opening 1 and 7.2m x
1.5m for Opening 2;
The breadth x length x height of the compartment is 7m x 14m
x3m;
Use Annex E of the Eurocode 1(Part 1-2) to determine the fire
load density (MJ/m2
) incorporating appropriate factor of safety.
Plot the temperature-time curve of the compartment fire for this office.
(Q3) The wall of an industrial furnace is constructed from 150mm thick fireclay
brick having a thermal conductivity k=1.7W/mK. Measurements make
during steady state operation reveal temperatures of 1400K and 1150K
at the inner and outer surfaces, respectively. What is the rate of heat
loss through a wall that is 500mmx1200mm on a side?
(Q4) Discuss and compare the ‘standard temperature-time curve (ISO834)’
and the ‘parametric temperature-time curve (based on EN 1991-1-2)’.
Assume that you are a fire engineer for a design task of structural fire
resistant design in several compartment fire scenarios. How do you plan
to incorporate both aforementioned fire curves in your work?
(Q5)
(a) Calculate the heat of combustion (∆Hc) of methanol (CH3OH) in
liquid form for complete combustion based on the given data on
heat of formation (∆Hf)
(b) Write down the chemical reaction for incomplete combustion of
methanol with CO and water vapour as products and hence
estimate related heat released per mole of methanol consumed
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(c) Discuss the errors for estimating possible heat released in real fire
cases based on the results in part (a) and (b) with related
assumptions
Source: Table 1.1 Glassman, I. and Yetter, R. A., 2008, Figure 4.3,
Combustion 4th Edition, Chapter 4, Section B, Page 6, Academic Press
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(Q6) Based on View Factor F12 and View Factor Fd1-2. , establish the
corresponding view factor between ceiling and a small fire on floor level
at different locations (i) at centre, (ii) at the middle of side wall and (iii)
at the corner of room with dimensions LxWxH
Source: Figure A.2 and A.6, SFPE, 2016, SFPE Handbook of Fire Protection
Engineering 5th Edition, Appendix A, Pages 3477 and 3481
Y
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(Q7) Based on the equation used to calculate upper layer temperature,
analyze the variation of the results due to the changes in ambient
temperature change from 280K to 310K for winter and summer
respectively with proper assumption(s). Hence, deduce the
corresponding impact on fire engineering analysis on fire resistance.
where ΔTg is the upper gas temperature rise above ambient, K;
Q is the heat release rate of fire, kW
g is the gravitational acceleration, 9.8 m/s2
cp is the specific heat capacity of air, J/(kg K)
ρ is the density of air, kg/m3
T is the ambient air temperature, K
Ao is the opening area, m2
Ho is the opening height, m
AT is the total area of compartment enclosing surface, m2
hk is the heat transfer coefficient
(Q8) (a) Analyze the effect of the heat transfer coefficient of wall and ceiling
materials for compartment fire development based on sketches of
Semenov Diagram.
(b) Hence, discuss the corresponding differences on the heat loss to
external for same compartment i) standalone like a bungalow and ii)
located deep inside a building.
(Q9)
(a) Differentiate between zone model and field model
(b) Give examples of simulation models for zone model and field model
(c) What are the concepts of zones?
(d) What is the importance in CFD model?
Sample Solution
