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8/11/2019 JDD - Alvin
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A STUDY OF THE PRECURSORS TO BACKDRAFT (SMOKE
EXPLOSION) IN A MECHANICALLY-VENTILATED
COMPARTMENT AND THE ROLE OF SOOT IN THIS
PHENOMENON
PhD student : Alvin Si-Xian LOO
Supervisors: Prof. Alexis COPPALLE (CORIA), Philippe AÎNE (AREVA)
10ème Journée des Doctorants du CORIA 2013
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
WHAT IS A B ACKDRAFT?
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
1 Ignition
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
1 Ignition
2 Fire growth
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
1 Ignition
2 Fire growth
3 Burning if all combustible materiels
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
1 Ignition
2 Fire growth
3 Burning if all combustible materiels
4 Fire decay due to lack of fuel
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
1 Ignition
2 Fire growth
3 Burning if all combustible materiels
4 Fire decay due to lack of fuel
5 Extinction of fire
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
F i r e p o w e r ( W )
Time (t)
Underventilated case + Backdraft
1 Ignition
2 Fire growth
3 Burning if all combustible materiels
4 Fire decay due to lack of fuel
5 Extinction of fire
1 2 3 4
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
F i r e p o w e r ( W )
Time (t)
Underventilated case + Backdraft
1 Ignition
2 Fire growth
3 Burning if all combustible materiels
4 Fire decay due to lack of fuel
5 Extinction of fire
1 2 3 4
1 Ignition
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
8/11/2019 JDD - Alvin
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
F i r e p o w e r ( W )
Time (t)
Underventilated case + Backdraft
1 Ignition
2 Fire growth
3 Burning if all combustible materiels
4 Fire decay due to lack of fuel
5 Extinction of fire
1 2 3 4
1 Ignition
2 Fire growth
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
8/11/2019 JDD - Alvin
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Lets start by examining the different stages of the fire power development in a
compartment during an accidental fire:
Well-ventilated case
WHAT IS A B ACKDRAFT?
F i r e p o w e r ( W )
Time (t)
F i r e p o w e r ( W )
Time (t)
Underventilated case + Backdraft
1 Ignition
2 Fire growth
3 Burning if all combustible materiels
4 Fire decay due to lack of fuel
5 Extinction of fire
1 2 3 4
1 Ignition
2 Fire growth
3 Fire decay due to lack of air
+ accumulation of combustible
vapor and soot
J o urn
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d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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WHAT IS A B ACKDRAFT?
Limited ventilation during an enclosure fire can lead to the production of large
amounts of unburnt pyrolysis products. When an opening is suddenly
introduced, the inflowing air forms a gravity current and begins to mix with
the unburned pyrolysis products,creating a combustible mixture of gases in
some part of the enclosure. Any ignition sources, such as a glowing ember, can
ignite this combustible mixture. Resulting in an extremely rapid burning of
gases/pyrolysis products forced out through the opening and causes a fireball
outside the enclosure. 15-- Fleischmann/Pagni/Quintiere
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WHAT IS A B ACKDRAFT?
Limited ventilation during an enclosure fire can lead to the production of large
amounts of unburnt pyrolysis products. When an opening is suddenly
introduced, the inflowing air forms a gravity current and begins to mix with
the unburned pyrolysis products,creating a combustible mixture of gases in
some part of the enclosure. Any ignition sources, such as a glowing ember, can
ignite this combustible mixture. Resulting in an extremely rapid burning of
gases/pyrolysis products forced out through the opening and causes a fireball
outside the enclosure. 16-- (Fleischmann/Pagni/Quintiere)
Backdraft is sometimes called ‘smoke explosion’
J o urn
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d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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CONTENTS OF THIS PRESENTATION
What is a Backdraft?
Context and Objectives of this study
Experimental apparatus for underventilated fires
Some Results of underventilated fires
Experimental apparatus for smoke deflagration
J o urn
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d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
To prevent radioactive substance leak, compartments are
sealed to ensure air-tightness. Mechanical ventilation
systems maintain an underpressure and renew the air of
the compartment
Study fire scenarios in nuclear installations.
Air
Smoke
J o urn
é e
d e s
D o
c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
To prevent radioactive substance leak, compartments are
sealed to ensure air-tightness. Mechanical ventilation
systems maintain an underpressure and renew the air of
the compartment
Study fire scenarios in nuclear installations.
Problem: Maintain confinement within thecompartments during fires Air
Smoke
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
To prevent radioactive substance leak, compartments are
sealed to ensure air-tightness. Mechanical ventilation
systems maintain an underpressure and renew the air of
the compartment
Study fire scenarios in nuclear installations.
Problem: Maintain confinement within thecompartments during fires
- Radioactive substance leak to the outside
- Damage of safety equipments in the compartment or in the ventilationnetwork (filters, doors, dampers…etc)
What could happen:
Air
Smoke
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
To prevent radioactive substance leak, compartments are
sealed to ensure air-tightness. Mechanical ventilation
systems maintain an underpressure and renew the air of
the compartment
Study fire scenarios in nuclear installations.
Problem: Maintain confinement within thecompartments during fires
- Radioactive substance leak to the outside
- Damage of safety equipments in the compartment or in the ventilationnetwork (filters, doors, dampers…etc)
Feared events: - Overpressure caused by the fire
- Temperatures inside the compartment becomes too high
- Backdraft
What could happen:
Air
Smoke
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
Overpressure and high temperatures can be caused by the fire itself:
(Internal energy of the compartment)
Backdraft can happen:
- Smoke dilution in the ventilation network
- Opening of doors by rescue personnels
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
Overpressure and high temperatures can be caused by the fire itself:
(Internal energy of the compartment)
Backdraft can happen:
- Smoke dilution in the ventilation network
- Opening of doors by rescue personnels
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
Overpressure and high temperatures can be caused by the fire itself:
(Internal energy of the compartment)
Backdraft can happen:
- Smoke dilution in the ventilation network
- Opening of doors by rescue personnels
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
Overpressure and high temperatures can be caused by the fire itself:
(Internal energy of the compartment)
So it is important to be able to predict correcly the power generated by the fire.
Backdraft can happen:
- Smoke dilution in the ventilation network
- Opening of doors by rescue personnels
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
- Interaction between the fire and its confined environment
which is under-oxygenated and polluted.
- Aeraulic pertubation caused by the mechanical ventilation
Overpressure and high temperatures can be caused by the fire itself:
(Internal energy of the compartment)
So it is important to be able to predict correcly the power generated by the fire.
Difficulty:
Backdraft can happen:
- Smoke dilution in the ventilation network
- Opening of doors by rescue personnels
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
- Interaction between the fire and its confined environment
which is under-oxygenated and polluted.
- Aeraulic pertubation caused by the mechanical ventilation
Overpressure and high temperatures can be caused by the fire itself:
(Internal energy of the compartment)
So it is important to be able to predict correcly the power generated by the fire.
Difficulty:
Backdraft can happen:
- Smoke dilution in the ventilation network
- Opening of doors by rescue personnels
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2 0 1
3
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CONTEXT OF THIS STUDY
- Interaction between the fire and its confined environment
which is under-oxygenated and polluted.
- Aeraulic pertubation caused by the mechanical ventilation
Overpressure and high temperatures can be caused by the fire itself:
(Internal energy of the compartment)
So it is important to be able to predict correcly the power generated by the fire.
Difficulty:
Backdraft can happen:
- Smoke dilution in the ventilation network
- Opening of doors by rescue personnels
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2
0 1
3
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1. Behavior of underventilated fires in a
mechanically-ventilated compartment.• Underventilated fires in confined
compartments must occur before the
conditions favourable to Backdraft can
be created.
• Experimental study using a reduced-
scale 1m3 compartment (fire chamber)
OBJECTIVES OF THIS STUDY
J o urn
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d e s
D o c t or
an
t s
C O R I A
2
0 1
3
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CONTENTS OF THIS PRESENTATION
What is a Backdraft?
Context and Objectives of this study
Experimental apparatus for underventilated fires
Some Results of underventilated fires
Experimental apparatus for smoke deflagration
J o urn
é e
d e s
D o c t or
an
t s
C O R I A
2
0 1
3
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Diagram of the experimental apparatus for studying underventilated fires in a