Computational Model of Smoldering Combustion with Chemical Kinetics (Phd Thesis Revisited)

8/7/2019 Computational Model of Smoldering Combustion with Chemical Kinetics (Phd Thesis Revisited)

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Guillermo Rein

Department of Mechanical Engineering

University of California at Berkeley, USA

Presentation originally given in December 2005, California

Remake in March 2011, Scotland

Computational Model of Forward andComputational Model of Forward andComputational Model of Forward andComputational Model of Forward andOpposed Smoldering Combustion withOpposed Smoldering Combustion withOpposed Smoldering Combustion withOpposed Smoldering Combustion with

Improved Chemical KineticsImproved Chemical KineticsImproved Chemical KineticsImproved Chemical Kinetics

Rein, PhD. Thesis, University of California at Berkeley, 2005http://repositories.cdlib.org/cpl/fs/ReinPhD05


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3/27

Smouldering Fire SafetyFirst leading cause of fire deaths (25% of

the total) due to:Difficult to detect

Higher yield of toxic gases

Sudden transition to flaming

Fire safety in space flights

Rein, International Review of Chemical Engineering, 2009.http://hdl.handle.net/1842/2678


4/27

Transition to Flaming Combustion

30 min1 h 1 s1 s

Torero 1992, UCB


5/27

Smoldering CombustionSmoldering CombustionSmoldering CombustionSmoldering CombustionHeterogeneous reactions at solid surface

Weak combustion inside porous materials

Low temperature (~500 C)Low heat release rate (~5 kJ/g-O2)

Slow propagation (~0.1 mm/s)

Rein,Int

ernationalRevie

wofChemicalE

ngineering,200

9.

http://hdl.handle.net/

1842/2678


6/27

ObjectiveObjectiveObjectiveObjective(knowledge on smoldering is very immature)

Solve the chemical inconsistency between forward

an opposed smouldering which have beenexperimentally observed to be controlled bydifferent kinetics


7/27

Virgin foam

Degraded foam Char


8/27

Method to Extract Parameters:Method to Extract Parameters:Method to Extract Parameters:Method to Extract Parameters:

Inverse ModellingInverse ModellingInverse ModellingInverse Modelling

1. Experimental data2. Kinetic mechanism

3. Mathematical Model

4. Optimization

Extract kinetic parameters


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ThermogravimetricThermogravimetricThermogravimetricThermogravimetric curvescurvescurvescurves

Data from Chao and Wang, JFS 2001


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Mechanism: 5 heterogeneous reactions + 4solid species

New 5New 5New 5New 5----step Mechanismstep Mechanismstep Mechanismstep Mechanism

Foam pyrolysis:

-foam pyrolysis:

Foam oxidation:

-foam oxidation:

Char oxidation:

Gasfoam-Foam pgp,p, +

GasCharfoam- pgp,pc, +

GasCharOFoam ogp,oc,2o,O2 ++

GasCharOfoam- ogp,oc,2o,O2 ++

GasResidueOChar cgp,cr,2c,O2 ++

Rein et al., Combustion and Flame, 2006.http://hdl.handle.net/1842/894


11/27

0-Dimensional transient model

Comparison to experiments5-step => 16 parameters (!)

MassMassMassMass----loss Modelloss Modelloss Modelloss Model

2O

n

0

iRTE

ii yW

WeA

iia

=

&

( ) cc,rooo,cpp,cpp,0

r

0

c

00

f

0

)1()1()1()1(

m

m

dt

d

m

m

dt

d

m

m

dt

d

m

m

dt

d

m

m

dt

d

++++

=

+

+

+

=

&&&&&



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Steps in Genetic Algorithms


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5555----step TG curvesstep TG curvesstep TG curvesstep TG curves



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Kinetic ParametersKinetic ParametersKinetic ParametersKinetic ParametersParameter Best Range Units

pE 148 [136, 160] kJ/mol

log10( pA ) 11.3 [10.4, 12.5] log10(1/s)

pn 0.21 [0.13, 0.31] -

p, 0.70 [0.69, 0.71] kg/kg

pE 124 [121, 127] kJ/mol

log10( pA ) 8.2 [7.8, 8.5] log10(1/s)

pn 1.14 [1.12, 1.18] -

p,c 0.05 [0.04, 0.06] kg/kg

oE 194 [161, 220] kJ/mol

Log10( oA ) 15.4 [12.6, 16.7] log10(1/s)

on 0.52 [0.47, 0.69] -

o,c 0.57 [0.55, 0.57] kg/kg

oE 194 [161, 220] kJ/mol

Log10( oA ) 15.4 [12.6, 16.7] log10(1/s)

on 0.52 [0.47, 0.69] -

o,c 0.57 [0.55, 0.57] kg/kg

cE 201 [193, 220] kJ/mol

log10( cA ) 15.2 [14.5, 16.7] log10(1/s)

cn 1.23 [1.10, 1.49] -

c,r 0.23 [0.21, 0.25] kg/kg

Reinetal.,CombustionandFlame,2006.

htt

p://hdl.handle.net/1842/894


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Model of SmoulderingMomentumMomentumMomentumMomentum transfer in porous mediaHeatHeatHeatHeat transport by: Conduction, Radiation and

Convection

MassMassMassMass transport by: Convection and DiffusionChemical ReactionsReactionsReactionsReactions in the solid/gas interface:

Pyrolysis and Oxidations

Rein et al., Proceedings of the Combustion Institute, 2007.http://hdl.handle.net/1842/897


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Mechanisms in Smouldering Ip

K=

uuuu

MW

gRTp g=

( ) ( ) ( )vvt jjgg +=

&

uuuu

MomentumMomentumMomentumMomentum

ContinuityContinuityContinuityContinuity

State LawState LawState LawState Law

~0gRein et al., Proceedings of the Combustion Institute, 2007.http://hdl.handle.net/1842/897


17/27

Mechanisms in Smouldering II( ) ( )( )

( ) ( )0sL

esg

gs

gs

jjj0p

TTV

AUTTV

A

h

hTTcTkt

h

+

+=

&uuuu

EnergyEnergyEnergyEnergy



18/27

Mechanisms in Smouldering III( ) +=

jj,ijii

2i yyDt

y&uuuu

SpeciesSpeciesSpeciesSpecies=

j j,ij

i

t

m&



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Mechanisms in Smouldering IV



20/27

Computational ModelComputational ModelComputational ModelComputational Model

Equationsdiscretized withfinite-differences

System of 9

ODEs per node(solved in timeusing the stiff

integrator)


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Modelling vs. ExperimentsOpposedOpposedOpposedOpposed ForwardForwardForwardForward

Bar-Ilan, Combustion Science and Technology, 2004.http://repositories.cdlib.org/postprints/350 Bar-Ilan, Experimental Thermal and Fluid Science, 2004http://repositories.cdlib.org/postprints/341


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Contribution: 1D Front Structure

OpposedOpposedOpposedOpposed ForwardForwardForwardForward



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NEW: Propagation vs. AirflowNEW: Propagation vs. AirflowNEW: Propagation vs. AirflowNEW: Propagation vs. Airflow



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Novel and efficient determination of

solid-phase kinetics

New PU mechanismModel reproduces most important

features of both opposed and forward1D smouldering

This is a major a improvement in the

modeling of smoldering combustionopening the door to 2D/3D modelling

ConclusionsConclusionsConclusionsConclusions

Rein, PhD. Thesis, University of California at Berkeley, 2005http://repositories.cdlib.org/cpl/fs/ReinPhD05


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Dissertation Committee:

Prof. Fernandez-PelloProf. Chen

Prof. Stephens

Am I a Ph.D. now?

Research sponsored by NASA

Collaborators:

Urban, Torero, Lautenberg,

Putzeys, Kallman, Bar-Ilan


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PhD Journal PublicationsPhD Journal PublicationsPhD Journal PublicationsPhD Journal Publications

Rein et al., Proceedings of the Combustion Institute, 2007.

http://hdl.handle.net/1842/897Rein et al., Combustion and Flame, 2006.http://hdl.handle.net/1842/894

Rein et al., Proceedings of the Combustion Institute, 2005.http://escholarship.org/uc/item/3104664p

Bar-Ilan et al., Combustion Science and Technology, 2004.http://repositories.cdlib.org/postprints/350

Bar-Ilan et al., Experimental Thermal and Fluid Science, 2004http://repositories.cdlib.org/postprints/341

Rein, International Review of Chemical Engineering, 2009.http://hdl.handle.net/1842/2678


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Contributions are decided by community and time

Manuscript style thesis, papers vs traditional chapter

Much larger empathy with audienceMuch more on Why is this importantHead of Mouse or Lion's tail?

Prepared for incoming quest: Head of Lion

What I would do differentWhat I would do differentWhat I would do differentWhat I would do different

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Computational Model of Smoldering Combustion with Chemical Kinetics (Phd Thesis Revisited)

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