M J G ll T H i k A S R l J P i d F A Willi 1 UC San Diego, 2 - - PowerPoint PPT Presentation
M. J. Gollner ,1 , T. Hetrick 2 , A. S. Rangwala 2 , J. Perricone 3 , and F. A. Williams 1 M J G ll T H i k A S R l J P i d F A Willi 1 UC San Diego, 2 Worcester Polytechnic Institute Worcester Polytechnic Institute 3 Schirmer Engineering 1
M J G ll T H i k A S R l J P i d F A Willi
1 UC San Diego, 2 Worcester Polytechnic Institute
Worcester Polytechnic Institute
3 Schirmer Engineering
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Plastic G A C Group A‐C
Warehouse Commodity
Class I ‐IV Classify grouped Use large scale test Warehouse commodity (Carton, packaging, plastic) commodity into
hazard groups (Based on HRR) Use large‐scale test data to design fire protection system (NFPA 13) plastic) (Based on HRR)
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Current classification uses ranking scheme (Model is based
Ranking influenced by a number of flammability
Intermediate‐scale measurements generate this parameter The sprinkler industry prefers full‐scale fire tests as
1Zalosh, R. G., Industrial Fire Protection Engineering. John Wiley and Sons, 2003
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2007 – Tupperware storage
2007 Tupperware storage warehouse fire1
15,392m2 warehouse burned for
24 hours – a total loss
Sprinklers met state & local
requirements including NFPA 13 requirements including NFPA 13 but the fire could not be extinguished once plastic became i l d
Warehouse fires pose significant risks to occupants, local environments, and responding fire personnel
involved
2007 – Furniture warehouse fire kills
9 firefighters in Charleston, SC.2
and responding fire personnel
(Photo: Georgetown Country Fire Dept. Hemingway, SC)
9 firefighters in Charleston, SC.
1The Problem with Big, NFPA Journal, March/April 2009 2Nine Career Fire Fighters Die in Rapid Fire Progression at Commercial Furniture Showroom
– South Carolina, Fire Fatality Investigation Report, NIOSH. 4
Large/Full Scale Current Research
Small Scale Testing
Intermediate Scale Testing (Proof of concept) Large/Full Scale Modeling (Proof of concept)
g Commodity type classification
p ) Cone Calorimeter testing Engineering Approach to Commodity Engineering Approach to Commodity Classification
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Boundary layer
Buoyant Plume B is a function of:
Combusting Plume Buoyant Plume
Plume Radiative + Convective Heat Transfer
Commodity
flame
Pyrolyzate Excess
′′
Combusting Plume
Flame Radiative + Convective Heat Transfer
XF
(~ 20 to 25 cm Laminar
Y‐axis
F
m′′
d b d XP
( 0 to 5 cm aminar Flame Propagation)
Corrugated board
provides physical understanding of the problem
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Boundary layer
Buoyant Plume
Plume Radiative + Convective Heat Transfer
Combusting Plume
Flame Radiative +
B is a function of:
Pyrolyzate Excess
Convective Heat Transfer
Commodity y py y p
F
m′′
Zone XP XF
(Turbulent flame height >25 cm)
flame Zone
Y‐axis Corrugated board
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Buoyant Plume
Plume Radiative + Convective Heat Transfer
Combusting Plume
flame
Excess
Flame Radiative + Convective Heat Transfer (from pool and wall fire)
B is a function of:
3 Commodity
Pyrolyzate
Commodity
X
Boundary layer
F
m′′
Corrugated board Solid/Liquid Pool fire XF
Boundary layer
Pyrolysis Zone
′′
Y‐axis Commodity leakage
F
m′′ Pyrolysis
Zone
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Non‐Dimensional FPI used to quantify flame spread q y p FPI = Fire Propagation Index ~ ρ = Flame Density ∆Hg = Heat of gasification q ‘’ Feedback flux
*
/
f g R
FPI FPI FPI q H V ρ = = ′′Δ
qf = Feedback flux VR = Regression velocity Non‐Dimensional Flux to quantify heating flux from the
CHF
burning commodity CHF = Critical Heat Flux (flux which will cause material to ignite) HRR = Average heat‐release rate of material
HRR CHF CHF =
*
HRR Average heat release rate of material
, ,
(1 )( ) / ( )
c O s p p
H Y C T T B H Q χ ν
∞ ∞ ∞
− Δ − − = Δ B‐number
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g
H Q Δ +
( )
i t i h t f b ti f b i
“ h d ”
( ) ( )
impetuses i.e. heat of combustion for burning resistances i.e. heat of vaporization to the process B= ∑
“Thermodynamic Driving Force”
(1 )( ) / ( ) H Y C T T Δ
, ,
(1 )( ) / ( )
c O s p p g
H Y C T T B H Q χ ν
∞ ∞ ∞
− Δ − − = Δ + B‐number
T∞ = Ambient temperature [K] L = Latent heat of vaporization [kJ/kg] ∆Hc = Heat of gasification [kJ/kg] Cp,f = Specific heat of the fuel [kJ/kg‐K] Q = L + Cp,f(TB‐TR) [kJ/kg] χ = Fraction of radiation lost [‐] ∆Hc = Heat of combustion [kJ/kg] YO,∞ = Mass fraction of oxygen in ambient [‐] νs = Oxygen‐fuel mass stoichiometric ratio [‐] Cp,∞ = Specific heat of ambient air [kJ/kg‐K] T P l i t t f th f l [1] Kanury, A. M. An Introduction to Combustion Phenomena. s.l. : Gordon & Breach Science Publishers, Inc, 1977. 10 Tp = Pyrolysis temperature of the fuel
b d i l b
[1]
be measured in a laboratory
ln(B 1)
f g
h m c ′′ = +
coefficient a formula for estimating an average B‐number based on measured
g
rate of mass loss is
1/3 ''
B exp 1 0.13[GrPr]
g g f
m ρ α ⎛ ⎞ = − ⎜ ⎟ ⎜ ⎟ ⎝ ⎠
g
ρ ⎝ ⎠
[1] Kanury, A. M. An Introduction to Combustion Phenomena. s.l. : Gordon & Breach Science Publishers, Inc, 1977. 11
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20 25 30 35 5 10 15
PMMA PP PS PE PC Doug Fir PVC
4 5 6 1 2 3
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1
PMMA PP PS PE PC Doug Fir PVC
Class III Commodity Group‐A Plastic Commodity
Standard Group‐A Plastic Commodity Standard Group‐A Plastic Commodity Polystyrene cups in compartmented cardboard carton
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30 s 92 s 100 s 132 s 150 s
Front Face of Cardboard Burning Plateau PS Cups & Cardboard Burning
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,
Mass Loss Rate
0.014 0.016 /m2*s]
'' f
m
(CB + Packing PS Cups 0.008 0.01 0.012 ss Rate [kg/ Front face of CB burning (CB + Packing material) Cups 0 002 0.004 0.006 Mass Los burning 50 100 150 0.002 Time from Ignition, [s] Begin Water
CB = Cardboard PS = Polystyrene
Application (to extinguish fire)
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4 5 B-number, Test 1 4 5 B-number, Test 2
Steady Initial
2 3 B 2 3 B
Steady Burning Region Initial Burning Region
20 40 60 80 100 120 140 1 Time from Ignition, [s] 50 100 150 200 1 Time from Ignition, [s]
4 5 B-number, Test 3 4 5 B-number, Test 4 1 2 3 B 1 2 3 B 50 100 150 Time from Ignition, [s] 50 100 150 Time from Ignition, [s]
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Experiments also measured flame height.
& Sibulkin*
2 1/3 1/2 1/2 ,0 2 ,
4(1 1.25( /B) ) ( ) * *( ) ( )
p p s p s s g
r x x t t c k T T α π ρ
∞
⎛ ⎞ ⎛ ⎞ − − = − ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ − ⎝ ⎠ ⎝ ⎠
2 1/4 7/4 , 0.19 1/4 1/2
/ ( / ) B 0.27 . (B 1) Pr ln(B 1)
c s c s p g
H g H c T r ν ν α
∞
Δ Δ = + +
2/3
0.64( /B)
f p
x r x
−
Φ = =
*Annamalai, K. and Sibulkin, M. Flame spread over combustible surfaces for laminar flow systems. Part I & II: Excess fuel and heat flux. 1979, Combust. Sci. Tech., vol. 19, pp. 167‐183.
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1100 Measured vs. Predicted Flame Heights 800 900 1000
Cone Calorimeter Testing B‐numbers measured in
600 700 800 ght (cm)
this test
400 500 Flame Heig 100 200 300 18 10 20 30 40 50 60 70 80 90 100 Time (s)
A new method of hazard ranking is introduced in this study based on
nondimensional parameters: B, FPI*, and CHF*
In a warehouse setting, where the burning rate is the dominant fire
hazard, the B‐number may appropriately classify the hazard of a grouped commodity – especially if we can correlate FPI* and CHF* with B
These parameters can be determined by small‐scale laboratory tests
The B‐number can be calculated by the Cone Calorimeter and/or
grouped commodity tests
FPI* can be determined using current testing methods by incorporating
parameters already measurable on the NIST LIFT apparatus
CHF* could possibly be determined by testing of a single grouped
warehouse commodity warehouse commodity
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These parameters are nondimensional and in preliminary
The economic advantage of predicting full‐scale
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Correlate FPI* and CHF* with the B‐number Perform small‐scale testing on the Cone Calorimeter of
Test the applicability of these nondimensional groups
Incorporate suppression – minimum suppressant (water
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