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2. CollaborationProf. Ali Rangwala Fire Protection Eng. WPITodd Hetrick MS Student, WPI Small Scale TestingKris Overholt M.S. Student, WPI Small-Scale TestingCecilia Florit, French Exchange Student Heat Flux MeasurementsJonathan Perricone Creative FPE Solutions, Inc. Industry ConsultantOpening picture from Bruce Smith, AP, 6/20/07, Charleston furniture warehouse where 9 firefighters died2 3. Outline I. Introduction to Commodity ClassificationII. Theory III. Experimental Setup IV. Experimental Data and Results V. Conclusion VI. Future Work3 4. I. Introduction to Commodity Classification4 5. Current Commodity Classification Plastic Group A-C Warehouse CommodityClass I -IVWarehouse 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. Recent Loss Case Example 2007 Tupperware storagewarehouse 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.2Warehouse fires pose significant risks to occupants, local environments, and responding fire personnel (Photo: Georgetown Country Fire Dept. Hemingway, SC)1TheProblem 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. 2Nine6 7. Shortcomings of Current Methodology Current classification uses ranking scheme (Model is based oncommodity 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 Dont Know about Storage, NFPA Presentation7 8. Sprinkler Warehouse Fire ModelingZalosh, Industrial Fire Protection Engineering, pg 159 8 9. Our ApproachCurrent ResearchSmall Scale Testing Commodity type classificationCone Calorimeter testingIntermediate Scale Testing (Proof of concept)Large/Full Scale Modeling(Proof of concept)Engineering Approach to Commodity Classification 9 10. Our Area of Contribution Computer Fire ModelingModel potential rack setups & sprinkler interactionsModeling used to test warehouse designs costeffectively, based on rankingCommodity ClassificationProvide input parametersAdd influence of large-scaleLarge-Scale Testing (Verification of both)Bench-scale tests determine nondimensional parameters (B)Rank commodities on fundamental scale used to design sprinkler system 11. Material Flammability Factors controlling flammability and fire hazard Ignition Fire Growth Burning Intensity Generation of Smoke and Toxic Compounds Extinction/Suppression11 12. Commodities Used in TestingClass IIClass IIIClass IV/Group BGroup A PlasticCommodities Used in Reality12 13. II. Theory13 14. Commodity Fire: Stage 1 Laminar Case Boundary layerB is a function of: 1. Corrugated boardBuoyant Plume Plume Radiative + Convective Heat TransferCommodityCombusting PlumeExcess PyrolyzatePyrolysis Zone mFFlame Radiative + Convective Heat TransferXFflameXP Flame height 25 cm Realistic fire situation Cardboard still intactPlume Radiative + Convective Heat TransferXPXF(Turbulent flame height >25 cm)flame Y-axis Corrugated board 15 16. Stage 3 Mixed Case Flame height >25 cm Realistic fire situation Cardboard breaks 16 17. Buoyant Plume Plume Radiative + Convective Heat TransferStage 3 Mixed Case Combusting Plume B is a function of: 1. Corrugated board 2. Commodity pyrolysis vapor Excess 3. Commodity PyrolyzateflameFlame Radiative + Convective Heat Transfer (from pool and wall fire)Commodity XF Solid/Liquid Pool fireCorrugated board m F Flame height >25 cm Realistic fire situation Polystyrene leaks and starts pool fireBoundary layerPyrolysis Zone mFCommodity leakagePyrolysisZoneY-axis 17 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 ForceB(1 )( H c YO , ) / s C p , (Tp T ) = Fraction of radiation lost [-] Hc = Heat of combustion [kJ/kg] YO, = Mass fraction of oxygen in ambient [-] s = Oxygen-fuel mass stoichiometric ratio [-] Cp, = Specific heat of ambient air [kJ/kg-K] Tp = Pyrolysis temperature of the fuelHg QB-numberT = 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. Reynolds Analogy Application to Warehouse Commodity Classification mF 1 Flow ConditionhTln(1 B )cg Material Properties2B-number19 20. Experimentally-Measured BSolving 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. III. Experimental Setup21 22. Experimental Setup Standard Group-A Plastic Commodity Polystyrene cups in compartmented cardboard carton22 23. Picture of Experimental Setup WPI, Summer 2008TC wires Heat flux sensorsBack ViewFront View23 24. Measurement of Heat Flux Thin-Skin CalorimeterCombined heat flux from calorimeter (accounting for losses)q i q c q r q sto q c , stqi qc qr q c , st q stoAmerican Society of Testing and Materials, Standard ASTM E 459-9724 25. IV. Experimental Results25 26. Commodity Test Results 30 s92 sFront Face of Cardboard BurningStage I100 s132 s150 sPlateauPS Cups & Cardboard BurningStage IIStage III 26 27. Commodity Test Results Video of test 327 28. 3 Stages of Burning28 29. Mass Lost29 30. Mass-Loss Rate Mass- Loss RateFront face burningPlateau RegionPS Cups30 31. Commodity Test Results Time-Varying B-numberB = 1.8B = 1.4B = 1.931 32. Heat Flux above the Commodity32 33. Thermocouple Measurements33 34. Commodity Test Results34 35. Commodity Test Results Summary of Stages Stage IStage IIStage IIIOuter 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.B1.8& m0.83 g/sX0.51 mf ,a vg& q f"1.2 kW/m2B1.4& m X f ,a vg1.7 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/s0.65 m 2.4 kW/m235 36. V. Conclusions36 37. Conclusions A new method of hazard ranking is suggested in this studybased 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. Conclusions Increasing CostsBench Scale TestsB-number YsSmall Scale TestsLarge Scale Tests38 39. Conclusions This parameter is nondimensional and in preliminary testspredictions 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. VI. Future Work40 41. Future Work Flame height prediction (including influence of radiation) Study possible correlations between B-number and otherrelevant 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 term41 42. Experimental setup to determine the water application rate g/cm2-s at different external heat fluxes flameLab air supply commodityExternal heat flux nozzlePan for water collection excess water collectorregulatorPressurized water supplyz (cm)water Water application rate g/cm2sLoad cell Load cell 42 43. Acknowledgements David LeBlanc at Tyco for generous donation of standardGroup A storage commodity and sharing full scale test data conducted at UL labs by Tyco. San Diego office of Schirmer Engineering for contributing startup funding at the beginning of the project. WPI Lab Manager Randy Harris, Research Assistants: CeceliaFlorit and Todd Hetrick, and helpful discussions with Jose Torero (University of Edinburgh) 43 44. Questions?44 45. Initial Flame Height PredictionsImportant for early-stage fire prediction, including sprinkler activation.45 46. Material Flammability46 47. Define a Baseline Curve (Class II) & make all other Curves Parallel47 48. Flame Spread Theory Many different theories of upward-spreading flames exist Annamalai & SibulkinXf~ A( B t )2 Saito, Quintiere, WilliamsXf~ Aet f (T R P, Xf ''f ) / X p,q1. 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. Sibulkin & Kim Yo , YF vsx f 0.64( r / B )2 / 3xpConvectionConvection + RadiationSibulkin and Kim, Comb. Sci. Tech. vol. 17, 197749 50. Variation of Fuel/Commodity Volume/Mass Ratios Experimental set up allows systematic control of twoimportant parameters at small scale: volume fuel / volume total commodity weight / packing material weight50 51. Proposed Experimental Setup Hood Detailed front view in next slideQuartz tube External heat flux IR lamps Extension plate Flow seedingAluminum tubeFlow straightener (honey comb mesh) O2 + N2 mixture Load cell 51 52. Noncombustible board 50 cmThinskin CalorimeterTS (b)insulation10 cmSide view camera50 cm Corrugated cardboardTCInsulationCorrugated cardboardPlastic/ packing material grid5cm Ignition trayDrip trayTo load cell52 53. Suppression Modeling Experimental set up allows variation of oxygen todetermine B-number at limits of burning53 54. burning rate g/cm2sTop view of experimental apparatus Plastic grid Volume fraction = 50 x 10 x 5 cm commodity Corrugated cardboard (outer cover)Zero water application (free burn)1.5 g/cm2sCritical mass flux (control)5 cm g/cm2s2 g/cm2s 3 g/cm2sz (cm) Critical mass flux (extinction)Radiant heaterIncreasing rate of water applicationWater spray nozzle g/cm2s0d c b a External heat flux, kW/m2Burning 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