subjected to transient irradiation Izabella Vermesi Guillermo Rein - - PowerPoint PPT Presentation

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subjected to transient irradiation Izabella Vermesi Guillermo Rein - - PowerPoint PPT Presentation

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One-dimensional model of pyrolysis and ignition of medium density fiberboard subjected to transient irradiation Izabella Vermesi Guillermo Rein Department of Mechanical Engineering Imperial College London Gaurav Agarwal FM Global Marcos

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SLIDE 1

One-dimensional model of pyrolysis and ignition of medium density fiberboard subjected to transient irradiation

Izabella Vermesi

Guillermo Rein

Department of Mechanical Engineering Imperial College London

Gaurav Agarwal

FM Global

Marcos Chaos

LLNL

15.11.2016 Torremolinos, ES

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SLIDE 2

Presentation Outline

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Pyrolysis under transient irradiation Previous work with polymers MDF: uses +

manufacture

MDF

experiments

MDF model

Constant + transient irradiation results Parametric study

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SLIDE 3

What is Pyrolysis?

2 Pyrolysis = the process through which the solid undergoes a chemical decomposition and transforms into a gaseous fuel

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SLIDE 4

Importance of Pyrolysis

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PYROLYSIS

Ignition

Flame spread

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SLIDE 5

Constant vs. transient

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5 10 15 20 25 30 500 1000 1500

Heat Flux [kW/m2] Time [s]

5 10 15 20 25 30 35 40 45 100 200 300 400 500

Heat Flux [kW/m2] Time [s]

5 10 15 20 25 30 35 500 1000 1500

Heat Flux [kW/m2] Time [s]

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SLIDE 6

Transient scenario: state of the art

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  • Linear ramps:
  • Wood: Univ. Zaragoza (2000), USTC (2007), USTC (2016)
  • MDF: FM Global (2016)
  • Polymers: Univ. Edinburgh (2012)
  • t2 parabolic heat flux:
  • Wood: USTC (2016), Univ. Waterloo (2016)
  • Parabolic pulses:
  • Forest fuels: Univ. Exeter (2015)
  • PMMA: Imperial College (2015)
  • MDF: Imperial College (2016)
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SLIDE 7

Vermesi et al., Combust. Fl. 2016

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SLIDE 8

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Vermesi et al., Combust. Fl. 2016

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SLIDE 9

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Vermesi et al., Combust. Fl. 2016

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SLIDE 10

Medium density fiberboard

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  • Engineered wood product obtained from wood fibers glued

together under heat and pressure

  • Use in the indoor built environment: furniture, separating

walls

http://ifabstudio.com/wp-content/uploads/2014/03/MDF_DETALE.jpg

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SLIDE 11

MDF experiments

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  • FPA experiments using MDF samples with thickness of 30 mm
  • Surface temperature measured with an IR pyrometer, mass

loss measured with load cell

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SLIDE 12

Irradiation Curves

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MDF model

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  • 1D model in Gpyro (Lautenberger, Fire Saf. J., 2009)

MDF

  • Boundary conditions:
  • Energy equation:
  • Arrhenius equation for pyrolysis rate
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SLIDE 14

MDF model

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SLIDE 15

MDF model

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SLIDE 16

MDF model

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SLIDE 17

MDF results: constant irradiation

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10 20 30 40 150 300 450 600 100 200 300 400 500

Irradiation [kW/m2] Temperature [°C] Time [s]

Measurement Model Predictions Irradiation

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SLIDE 18

MDF results: constant irradiation

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10 20 30 40 150 300 450 600 100 200 300 400 500

Irradiation [kW/m2] Temperature [°C] Time [s]

Measurement Model Predictions Irradiation

10 20 30 40 2 4 6 8 100 200 300 400 500

Irradiation [kW/m2] Mass loss rate [g/m2s] Time [s]

Measurement Model Predictions Irradiation

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SLIDE 19

MDF results: transient irradiation

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10 20 30 40 150 300 450 600 200 400

Irradiation [kW/m2] Temperature [°C] Time [s]

Measurement Model Predictions Irradiation

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SLIDE 20

MDF results: transient irradiation

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10 20 30 40 150 300 450 600 200 400

Irradiation [kW/m2] Temperature [°C] Time [s]

Measurement Model Predictions Irradiation

10 20 30 40 2 4 6 8 100 200 300 400 500

Irradiation [kW/m2]

Mass loss rate [g/m2s] Time [s]

Measurement Model Predictions Irradiation

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SLIDE 21

Parametric study

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  • Thermal properties that remain constant with

temperature vs. temperature-dependent properties

  • Influence of the drying step in the kinetics scheme
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Constant vs. temperature dependent properties

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Influence of drying

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Conclusions

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  • MDF subjected to transient irradiation ignited in all scenarios
  • MDF experiments modelled in 1D in Gpyro (no optimization, only

values from literature and measurements)

  • Surface temperatures are well predicted for both materials
  • Mass loss rate is predicted qualitatively
  • Drying is an essential step in modelling MDF
  • Using temperature dependent properties improves the results slightly,

but is not as influential as drying

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SLIDE 25

Thank you for your attention! Questions?

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Acknowledgements: