1
Collaboration

Prof. Ali Rangwala
Fire Protection Eng.
WPI

Todd Hetrick
MS Student, WPI
Small Scale Testing

Kris Overhol...
Outline
I. Introduction to Commodity Classification

II. Theory
III. Experimental Setup
IV. Experimental Data and Results
...
I. Introduction to
Commodity Classification

4
Current Commodity Classification
Plastic
Group A-C
Warehouse
Commodity

Class I -IV

Warehouse
commodity
(Carton, packagin...
Recent Loss Case Example
 2007 – Tupperware storage

warehouse fire1
 15,392 m2 warehouse burned for
24 hours – a total ...
Shortcomings of Current Methodology
 Current classification uses ranking scheme (Model is based on

commodity classificat...
Sprinkler Warehouse Fire Modeling

Zalosh, Industrial Fire
Protection
Engineering, pg 159
8
Our Approach

Current Research

Small Scale Testing
Commodity type
classification

Cone Calorimeter testing

Intermediate
...
Our Area of Contribution
Computer Fire
Modeling

Model potential rack setups
& sprinkler interactions

Modeling used to te...
Material Flammability
 Factors controlling flammability and fire hazard
 Ignition
 Fire Growth
 Burning Intensity
 Ge...
Commodities Used in Testing

Class II

Class III

Class
IV/Group B

Group A Plastic

Commodities Used in Reality

12
II. Theory

13
Commodity Fire: Stage 1 –
Laminar Case
Boundary layer

B is a function of:
1. Corrugated board

Buoyant Plume
Plume Radiat...
Stage 2 – Turbulent Case

Buoyant Plume

Boundary layer

B is a function of:
1. Corrugated board
2. Commodity pyrolysis va...
Stage 3 – Mixed Case

• Flame height >25 cm
• Realistic fire situation
• Cardboard breaks
16
Buoyant Plume
Plume Radiative +
Convective Heat Transfer

Stage 3 – Mixed Case
Combusting Plume
B is a function of:
1. Cor...
The B-number
B

 im petuses  i.e. heat of com bustion  for bu rning
 resistances  i.e. heat of vaporization  to the...
Reynolds Analogy
Application to Warehouse Commodity Classification

 
mF 
1
Flow
Condition

hT

ln(1  B )

cg
Materia...
Experimentally-Measured B

•Solving for B and using Nu correlation for the heat-transfer coefficient:
 ''

mf
B  exp 
...
III. Experimental Setup

21
Experimental Setup

 Standard Group-A Plastic Commodity
 Polystyrene cups in compartmented cardboard carton

22
Picture of Experimental Setup
WPI, Summer 2008

TC wires
Heat flux sensors

Back View

Front View

23
Measurement of Heat Flux
Thin-Skin Calorimeter

Combined heat flux from calorimeter
(accounting for losses)

q i  q c  q...
IV. Experimental Results

25
Commodity Test Results
30 s

92 s

Front Face of Cardboard
Burning

Stage I

100 s

132 s

150 s

Plateau

PS Cups & Cardb...
Commodity Test Results
Video of test 3

27
3 Stages of Burning

28
Mass Lost

29
Mass-Loss Rate
Mass- Loss Rate

Front face
burning

Plateau Region

PS
Cups

30
Commodity Test Results
Time-Varying B-number

B = 1.8

B = 1.4

B = 1.9

31
Heat Flux above the Commodity

32
Thermocouple Measurements

33
Commodity Test Results

34
Commodity Test Results
Summary of Stages
Stage I

Stage II

Stage III

Outer layer of commodity is ignited,
producing rapi...
V. Conclusions

36
Conclusions
 A new method of hazard ranking is suggested in this study

based on a nondimensional parameter: B
 In a war...
Conclusions
Increasing Costs

Bench
Scale
Tests

B-number
Ys

Small
Scale
Tests

Large
Scale
Tests

38
Conclusions
 This parameter is nondimensional and in preliminary tests

predictions from this parameter show good correla...
VI. Future Work

40
Future Work
 Flame height prediction (including influence of radiation)
 Study possible correlations between B-number an...
Experimental setup to determine the water application
rate ω g/cm2-s at different external heat fluxes
flame

Lab air supp...
Acknowledgements
 David LeBlanc at Tyco for generous donation of standard

Group A storage commodity and sharing full sca...
Questions?

44
Initial Flame Height Predictions

Important for early-stage fire prediction, including sprinkler activation.

45
Material Flammability

46
Define a
Baseline
Curve
(Class II) &
make all
other Curves
Parallel

47
Flame Spread Theory
 Many different theories of upward-spreading flames exist
 Annamalai & Sibulkin

X

f

~ A( B  t )
...
 Sibulkin & Kim
Yo ,
YF vs

x f  0.64( r / B )

2 / 3

xp

Convection

Convection +
Radiation

Sibulkin and Kim, Comb....
Variation of Fuel/Commodity
Volume/Mass Ratios
 Experimental set up allows systematic control of two

important parameter...
Proposed Experimental Setup
Hood
Detailed
front view in
next slide

Quartz tube
External heat flux
IR lamps
Extension plat...
Noncombustible
board
50 cm

Thinskin
Calorimeter

TS
(b)

insulation

10 cm

Side view
camera

50 cm
Corrugated
cardboard
...
Suppression Modeling
 Experimental set up allows variation of oxygen to

determine B-number at limits of burning

53
burning rate
g/cm2s

Top view of experimental
apparatus
Plastic grid
Volume fraction = Ф
50 x 10 x 5 cm
commodity
Corrugat...
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Gollner masters thesis presentation final jan 2010

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  • Initial funding for experiments was provided by Schirmer Engineering.
  • The goal of this study is to evaluate a method of characterizing the relative fire hazard of a grouped warehouse commodity. * Commodity classification refers to a ranking of estimated fire challenge to sprinkler protection.
  • Why are warehouse fires, and particularly upward spread problems being revisited for study? Examples of losses, where “fully-protected” facilities are still burning down despite what should be full protection. There are still glaring lacks of scientific understanding of the fire spread process, let alone suppression process for these large fires. This endangers firefighters, occupants, and local environments. Soot production and toxic runoffs from 2-day long fires are extreme.
  • Commodity classification in warehouse used to determine requirements of suppression system based on Area Density Curves. Full-scale fire tests are preferred by more than just the sprinkler industry. They give the best approximation available; however, there are several problems:By rushing to full-scale tests exclusively, we are glossing over the fundamental physics into something that is so complex that it defies clear comprehensionFull-scale testing is not always economically feasible or even physically possible (i.e. very tall rack storage arrangements)Free-burning HRR paints an incomplete picture. Several other driving and resisting influences govern combustion such as...Free-burning HRR is scale dependent. Ranking via intermediate scale measurements doesn’t necessarily translate into accurate full-scale assessment. The scale dependence may extend to multiple geometric dimensions (i.e. wood cribs).Are results repeatable? Tyco was unable to reproduce data points on the existing curves according to Golinveaux presentation at NFPA Conference 2007.Are results reproducible? Inconsistencies between NFPA and CENClassification by analogy is common industry practice. No testing performed. Analogies made in non-standard manner and generally very poorly substantiated (i.e. plastic totes in Tupperware facility in S.C.)Suppression and control are vaguely defined. The difference between them is unclear.The distinction between a fire under control and out of control is also unclear.
  • Goal is to make fire scenarios more predictable with scientifically verifiable results from testing. Distinguish & predict levels of fire control, suppression, and extinction for multiple commodities and layouts.Currently: Working on Cone Calorimeter (see other presentation) and small-scale testing on a standard commodity to determine non-dimensional parameters. Later will predict & assess accuracy of new methods with intermediate (Fire products collector) & large scale testing.
  • Our contribution is Bench-scale tests to determine nondimensional parameters, (B)Will be used to rank commodities on a fundamental scale used to design a sprinkler system.May also be useful as an input into modeling applications in the future.
  • Commodity classification in warehouse used to determine requirements of suppression system based on Area Density Curves. Full-scale fire tests are preferred by more than just the sprinkler industry. They give the best approximation available; however, there are several problems:By rushing to full-scale tests exclusively, we are glossing over the fundamental physics into something that is so complex that it defies clear comprehensionFull-scale testing is not always economically feasible or even physically possible (i.e. very tall rack storage arrangements)Free-burning HRR paints an incomplete picture. Several other driving and resisting influences govern combustion such as...Free-burning HRR is scale dependent. Ranking via intermediate scale measurements doesn’t necessarily translate into accurate full-scale assessment. The scale dependence may extend to multiple geometric dimensions (i.e. wood cribs).Are results repeatable? Tyco was unable to reproduce data points on the existing curves according to Golinveaux presentation at NFPA Conference 2007.Are results reproducible? Inconsistencies between NFPA and CENClassification by analogy is common industry practice. No testing performed. Analogies made in non-standard manner and generally very poorly substantiated (i.e. plastic totes in Tupperware facility in S.C.)
  • Laminar case is not a principal hazard but likely present in initial stages and useful for theoretical analyses.Corrugated board is ignited at the base, heats to a pyrolysis temperature where the board pyrolyzes expelling fuel vapors. Oxygen in the air diffuses towards this region and forms a thin diffusion flame at some standoff distance above the commodity. Not all of the fuel is burned directly in front of the pyrolysis region, some flows upwards beyond the pyrolysis zone into the combusting plume, where it burns above. This is called “excess pyrolyzate.” This excess pyrolyzate burning in the combusting plume heats the rest of the commodity incredibly fast as it burns in front of the surface, developing a very quickly growing upward spreading flame.
  • The same pyrolysis zone, combusting plume, and buoyant plume exist in this case. Now, the flame is larger and the combusting plume begins to extend above the height of the commodity surface, and the flame becomes very turbulent. The fire grows more rapidly. The remaining products are then propelled above into a buoyant plume.
  • In the mixed case the same processes still occur but now some leakage of the commodity (in the form of melted plastic) pool in front of the commodity. Now remaining cardboard burns as well as a small pool fire at the base of the commodity. The characteristics of the pool fire as well as the flat plate burning must be taken into account. In our tests, for safety reasons the fire was extinguished before significant commodity leakage occurred. We burnt approximately only 3/4 of the commodity. It would take upwards of 3-5 minutes for this to occur based on observations from tests, so characterizing the earlier region to involved suppression is more important for this study.
  • In the mixed case the same processes still occur but now some leakage of the commodity (in the form of melted plastic) pool in front of the commodity. Now remaining cardboard burns as well as a small pool fire at the base of the commodity. The characteristics of the pool fire as well as the flat plate burning must be taken into account. In our tests, for safety reasons the fire was extinguished before significant commodity leakage occurred. We burnt approximately only 3/4 of the commodity. It would take upwards of 3-5 minutes for this to occur based on observations from tests, so characterizing the earlier region to involved suppression is more important for this study.
  • “Universal Meaning”The B number can be thought of as a thermodynamic or mass transfer driving force. It was first introduced by Spalding in 1950 to develop an expression for the burning rate of a liquid fuel droplet in a gas stream. The uncorrected B-number is a property of pyrolyzing material, and it appears in boundary conditions of energy conservation at the fuel surface. The corrected B-number accounts for influences of additional heat-transfer processes. Physically, it relates the heat release of combustion (the numerator) to the energy required to generate fuel gasses (the denominator).In a mass-transfer sense it is the ratio of an impetus for interphase transfer to a resistance opposing that transfer.
  • Mf’’ is the mass loss rate per unit are of the material, which is related to the heat transfer component (h/Cg) times the thermodynamic component ln(B+1). Because of the log relationship of B, heat transfer plays a larger role in this process. H is assumed to be a constant in this process and is determined by a relation first relating it to the Nusselt number, and a nusselt number correlation which is a function of the cubed root of the Grashof number times Prandtl number. This approach is not exact, but for these small-scale experiments it is acceptable to ignore these small variations in h. Future work we are conducting will investigate the heat transfer coefficient numerically. The resulting formula for the average B number is an exponential function of the mass loss rate of the fuel per area over constants minus 1.
  • Deemphasize
  • Representative test
  • Shaded region denotes overlap between regions 1 & 2. Test timelines have been adjusted so transition between stage I and II lie on the same point on the time scale.
  • Shaded region denotes overlap between regions 1 & 2. Test timelines have been adjusted so transition between stage I and II lie on the same point on the time scale.
  • Shaded region denotes overlap between regions 1 & 2. Test timelines have been adjusted so transition between stage I and II lie on the same point on the time scale.
  • Time averaged mass loss rates used to calculate B-number over entire region. This B-number is an ESTIMATE in the region, it has been shown by Rangwala et al. that the B-number does change during upward spread, but deviations on average are minimal and results over this region are roughly repeatable for multiple tests.
  • Shaded region denotes overlap between regions 1 & 2. Test timelines have been adjusted so transition between stage I and II lie on the same point on the time scale.
  • Shaded region denotes overlap between regions 1 & 2. Test timelines have been adjusted so transition between stage I and II lie on the same point on the time scale.
  • Shaded region denotes overlap between regions 1 & 2. Test timelines have been adjusted so transition between stage I and II lie on the same point on the time scale.
  • Gollner masters thesis presentation final jan 2010

    1. 1. 1
    2. 2. Collaboration Prof. Ali Rangwala Fire Protection Eng. WPI Todd Hetrick MS Student, WPI Small Scale Testing Kris Overholt M.S. Student, WPI Small-Scale Testing Cecilia Florit, French Exchange Student Heat Flux Measurements Jonathan Perricone Creative FPE Solutions, Inc. Industry Consultant Opening picture from Bruce Smith, AP, 6/20/07, Charleston furniture warehouse where 9 firefighters died 2
    3. 3. Outline I. Introduction to Commodity Classification II. Theory III. Experimental Setup IV. Experimental Data and Results V. Conclusion VI. Future Work 3
    4. 4. I. Introduction to Commodity Classification 4
    5. 5. Current Commodity Classification Plastic Group A-C Warehouse Commodity Class I -IV Warehouse commodity (Carton, packaging, plastic) Classify grouped commodity into one of seven hazard groups (Based on HRR) Use large-scale test data to design fire protection system (NFPA 13) 5
    6. 6. Recent Loss Case Example  2007 – Tupperware storage warehouse fire1  15,392 m2 warehouse burned for 24 hours – a total loss  Sprinklers met state & local requirements including NFPA 13 but the fire could not be extinguished once plastic became involved  2007 – Furniture warehouse fire kills 9 firefighters in Charleston, SC.2 Warehouse fires pose significant risks to occupants, local environments, and responding fire personnel (Photo: Georgetown Country Fire Dept. Hemingway, SC) 1The Problem with Big, NFPA Journal, March/April 2009 Career Fire Fighters Die in Rapid Fire Progression at Commercial Furniture Showroom – South Carolina, Fire Fatality Investigation Report, NIOSH. 2Nine 6
    7. 7. Shortcomings of Current Methodology  Current classification uses ranking scheme (Model is based on commodity classification: Class I-IV, Group A-C Plastics) according to the free-burning heat-release rate (HRR)  Full-scale fire tests are preferred, but intermediate tests are more commonly used to assess Free-burning HRR & classification  Tests are not economically feasible  Free-burning HRR is scale dependent  Fundamental physics is glossed over  Tests have not been shown to be repeatable1  Classification by analogy presents a dangerous, yet common industry practice. (i.e. plastic totes in S.C. Tupperware facility) 1Golinveaux, “What We Don’t Know about Storage,” NFPA Presentation 7
    8. 8. Sprinkler Warehouse Fire Modeling Zalosh, Industrial Fire Protection Engineering, pg 159 8
    9. 9. Our Approach Current Research Small Scale Testing Commodity type classification Cone Calorimeter testing Intermediate Scale Testing (Proof of concept) Large/Full Scale Modeling (Proof of concept) Engineering Approach to Commodity Classification 9
    10. 10. Our Area of Contribution Computer Fire Modeling Model potential rack setups & sprinkler interactions Modeling used to test warehouse designs costeffectively, based on ranking Commodity Classification Provide input parameters Add influence of large-scale Large-Scale Testing (Verification of both) Bench-scale tests determine nondimensional parameters (B) Rank commodities on fundamental scale used to design sprinkler system
    11. 11. Material Flammability  Factors controlling flammability and fire hazard  Ignition  Fire Growth  Burning Intensity  Generation of Smoke and Toxic Compounds  Extinction/Suppression 11
    12. 12. Commodities Used in Testing Class II Class III Class IV/Group B Group A Plastic Commodities Used in Reality 12
    13. 13. II. Theory 13
    14. 14. Commodity Fire: Stage 1 – Laminar Case Boundary layer B is a function of: 1. Corrugated board Buoyant Plume Plume Radiative + Convective Heat Transfer Commodity Combusting Plume Excess Pyrolyzate Pyrolysis Zone   mF Flame Radiative + Convective Heat Transfer XF flame XP • Flame height <25 cm • Unrealistic in fire situation Corrugated board • Study important because provides physical understanding of the problem (~ 20 to 25 cm Laminar Flame Propagation) Y-axis 14
    15. 15. Stage 2 – Turbulent Case Buoyant Plume Boundary layer B is a function of: 1. Corrugated board 2. Commodity pyrolysis vapor Combusting Plume Flame Radiative + Convective Heat Transfer Excess Pyrolyzate Commodity   mF Pyrolysis Zone • Flame height >25 cm • Realistic fire situation • Cardboard still intact Plume Radiative + Convective Heat Transfer XP XF (Turbulent flame height >25 cm) flame Y-axis Corrugated board 15
    16. 16. Stage 3 – Mixed Case • Flame height >25 cm • Realistic fire situation • Cardboard breaks 16
    17. 17. Buoyant Plume Plume Radiative + Convective Heat Transfer Stage 3 – Mixed Case Combusting Plume B is a function of: 1. Corrugated board 2. Commodity pyrolysis vapor Excess 3. Commodity Pyrolyzate flame Flame Radiative + Convective Heat Transfer (from pool and wall fire) Commodity XF Solid/Liquid Pool fire Corrugated board  m  F • Flame height >25 cm • Realistic fire situation • Polystyrene leaks and starts pool fire Boundary layer Pyrolysis Zone   mF Commodity leakage Pyrolysis Zone Y-axis 17
    18. 18. The B-number B  im petuses  i.e. heat of com bustion  for bu rning  resistances  i.e. heat of vaporization  to the process “Thermodynamic Driving Force” B (1   )(  H c YO ,  ) /  s  C p ,  (Tp  T ) 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] Tp = Pyrolysis temperature of the fuel Hg  Q 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] [1] Kanury, A. M. An Introduction to Combustion Phenomena. s.l. : Gordon & Breach Science Publishers, Inc, 1977. 18
    19. 19. Reynolds Analogy Application to Warehouse Commodity Classification   mF  1 Flow Condition hT ln(1  B ) cg Material Properties 2 B-number 19
    20. 20. Experimentally-Measured B •Solving for B and using Nu correlation for the heat-transfer coefficient:  ''  mf B  exp     0.13[G r Pr]1 / 3  g g  1   •Formula for average B-number based on measured rate of mass loss •Applies in regimes dominated by convective heat transfer, as found in many small-scale experiments. •Effective B-number derived by same formula with radiation included Kanury, A. M. An Introduction to Combustion Phenomena. Gordon & Breach Science Publishers, Inc, 1977. 20
    21. 21. III. Experimental Setup 21
    22. 22. Experimental Setup  Standard Group-A Plastic Commodity  Polystyrene cups in compartmented cardboard carton 22
    23. 23. Picture of Experimental Setup WPI, Summer 2008 TC wires Heat flux sensors Back View Front View 23
    24. 24. Measurement of Heat Flux Thin-Skin Calorimeter Combined heat flux from calorimeter (accounting for losses) q i  q c  q r  q sto  q c , st qi qc qr q c , st q sto American Society of Testing and Materials, Standard ASTM E 459-97 24
    25. 25. IV. Experimental Results 25
    26. 26. Commodity Test Results 30 s 92 s Front Face of Cardboard Burning Stage I 100 s 132 s 150 s Plateau PS Cups & Cardboard Burning Stage II Stage III 26
    27. 27. Commodity Test Results Video of test 3 27
    28. 28. 3 Stages of Burning 28
    29. 29. Mass Lost 29
    30. 30. Mass-Loss Rate Mass- Loss Rate Front face burning Plateau Region PS Cups 30
    31. 31. Commodity Test Results Time-Varying B-number B = 1.8 B = 1.4 B = 1.9 31
    32. 32. Heat Flux above the Commodity 32
    33. 33. Thermocouple Measurements 33
    34. 34. Commodity Test Results 34
    35. 35. Commodity Test Results Summary of Stages Stage I Stage II Stage III Outer layer of commodity is ignited, producing rapid upward turbulent flame spread over the front face of a commodity. B is independent of polystyrene. Front layer of corrugated cardboard has burned to top, exposing inner region, which burns and then smolders. Polystyrene does not burn because of its higher ignition temperature. B 1.8 & m 0.83 g/s X 0.51 m f ,a vg & q f" 1.2 kW/m2 B 1.4 & m X f ,a vg 1.7 g/s & q f" Polystyrene ignites and a rapid increase B in the burning rate occurs. & m X f ,a vg & q f" 0.48m 0.38 kW/m2 1.9 2.2 g/s 0.65 m 2.4 kW/m2 35
    36. 36. V. Conclusions 36
    37. 37. Conclusions  A new method of hazard ranking is suggested in this study based on a nondimensional parameter: B  In a warehouse setting, where the burning rate is the dominant fire hazard, the effective B-number may appropriately classify the hazard of a grouped commodity  The B-number can be calculated using small-scale tests  Commodity Upward Spread via Mass Loss Rate  Cone Calorimeter Upward Spread via Mass Loss Rate (Overholt et al.)  Flame Standoff Distance (Rangwala et al.) 1. K.J. Overholt, M.J. Gollner, and A. Rangwala, "Characterizing Flammability of Corrugated Cardboard Using a Cone Calorimeter," Proceedings of the 6th U.S. National Combustion Meeting, 2009. 2. A.S. Rangwala, S.G. Buckley, and J.L. Torero, "Analysis of the constant B-number assumption while modeling flame spread," Combustion and Flame, vol. 152, 2008, pp. 401-414. 37
    38. 38. Conclusions Increasing Costs Bench Scale Tests B-number Ys Small Scale Tests Large Scale Tests 38
    39. 39. Conclusions  This parameter is nondimensional and in preliminary tests predictions from this parameter show good correlations to test data  The economic advantage of predicting full-scale performance with small-scale experiments may be an impetus for a significant evolution in the field of fire protection engineering. 39
    40. 40. VI. Future Work 40
    41. 41. Future Work  Flame height prediction (including influence of radiation)  Study possible correlations between B-number and other relevant flammability parameters (TRP, FPI, CHF, etc.)  Variation of Fuel/Commodity Volume/Mass Ratios  Incorporate suppression – minimum suppressant (water spray) can be incorporated in B-number via loss term 41
    42. 42. Experimental setup to determine the water application rate ω g/cm2-s at different external heat fluxes flame Lab air supply commodity External heat flux nozzle Pan for water collection excess water collector regulator  Pressurized water supply z (cm) water ω Water application rate g/cm2s Load cell Load cell 42
    43. 43. Acknowledgements  David LeBlanc at Tyco for generous donation of standard Group A storage commodity and sharing full scale test data conducted at UL labs by Tyco.  San Diego office of Schirmer Engineering for contributing start up funding at the beginning of the project.  WPI Lab Manager Randy Harris, Research Assistants: Cecelia Florit and Todd Hetrick, and helpful discussions with Jose Torero (University of Edinburgh) 43
    44. 44. Questions? 44
    45. 45. Initial Flame Height Predictions Important for early-stage fire prediction, including sprinkler activation. 45
    46. 46. Material Flammability 46
    47. 47. Define a Baseline Curve (Class II) & make all other Curves Parallel 47
    48. 48. Flame Spread Theory  Many different theories of upward-spreading flames exist  Annamalai & Sibulkin X f ~ A( B  t ) 2  Saito, Quintiere, Williams X f ~ Ae t   f (T R P, X f  ''f ) / X p,q 1. 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. 2. Saito, J.G. Quintiere, and F.A. Williams, "Upward Turbulent Flame Spread," Fire Safety Science-Proceedings of the First International Symposium, 1985, pp. 75-86. 48
    49. 49.  Sibulkin & Kim Yo , YF vs x f  0.64( r / B ) 2 / 3 xp Convection Convection + Radiation Sibulkin and Kim, Comb. Sci. Tech. vol. 17, 1977 49
    50. 50. Variation of Fuel/Commodity Volume/Mass Ratios  Experimental set up allows systematic control of two important parameters at small scale:  volume fuel / volume total  commodity weight / packing material weight 50
    51. 51. Proposed Experimental Setup Hood Detailed front view in next slide Quartz tube External heat flux IR lamps Extension plate Flow seeding Aluminum tube Flow straightener (honey comb mesh) O2 + N2 mixture Load cell 51
    52. 52. Noncombustible board 50 cm Thinskin Calorimeter TS (b) insulation 10 cm Side view camera 50 cm Corrugated cardboard TC Insulation Corrugated cardboard Plastic/ packing material grid 5cm Ignition tray Drip tray To load cell 52
    53. 53. Suppression Modeling  Experimental set up allows variation of oxygen to determine B-number at limits of burning 53
    54. 54. burning rate g/cm2s Top view of experimental apparatus Plastic grid Volume fraction = Ф 50 x 10 x 5 cm commodity Corrugated cardboard (outer cover) Zero water application (free burn) 1.5ω g/cm2s Critical mass flux (control) 5 cm ω g/cm2s 2ω g/cm2s 3ω g/cm2s z (cm)  Critical mass flux (extinction) Radiant heater Increasing rate of water application Water spray nozzle ω g/cm2s 0 d c b a External heat flux, kW/m2 Burning rate vs. external heat flux for various water application rates. Curves are hypothetical, based on experimental data reported by Magee and Reitz Magee, R.S. and R.D. Reitz, Extinguishment of radiation augmented plastic fires by water sprays. Proc. Combust. Inst. 15: p. 337-347. 54
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