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Gollner masters thesis presentation final jan 2010


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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