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COMBUSTION PHYSICS
Inthepastseveraldecades,combustionhasevolvedfromascientificdiscipline
thatwaslargelyempiricaltoonethatisquantitativeandpredictive.Thesead-
vancesarecharacterizedbythecanonicalformulationofthetheoreticalfoun-
dation;thestronginterplaybetweentheory,experiment,andcomputation;and
theunifieddescriptionoftherolesoffluidmechanicsandchemicalkinetics.This
graduate-leveltextincorporatestheseadvancesinacomprehensivetreatmentof
thefundamentalprinciplesofcombustionphysics.Thepresentationemphasizes
analytical proficiency and physical insight, with the former achieved through
complete, though abbreviated, derivations at different levels of rigor, and the
latterthroughphysicalinterpretationsofanalyticalsolutions,experimentalob-
servations,andcomputationalsimulations.Exercisesaredesignedtostrengthen
thestudent’smasteryofthetheory.Implicationsofthefundamentalknowledge
onpracticalphenomenaarediscussedwheneverappropriate.Thesedistinguish-
ingfeaturesprovideasolidfoundationforanacademicprogramincombustion
scienceandengineering.
ChungK.LawistheRobertH.GoddardProfessorofMechanicalandAerospace
EngineeringatPrincetonUniversity.Heobtainedhisdoctorateinengineering
physics from the University of California at San Diego in 1973. His research
interests are in combustion, propulsion, heat and mass transfer, and issues on
energyandtheenvironment.Forhisresearchaccomplishments,hereceivedthe
CurtisW.McGrawResearchAwardoftheAmericanSocietyforEngineering
Education(ASEE)in1984foroutstandingearlyachievementinresearch,asil-
vermedaloftheCombustionInstitutein1990,thePropellantsandCombustion
AwardoftheAmericanInstituteofAeronauticsandAstronautics(AIAA)in
1994,theHeatTransferMemorialAward,inscience,oftheAmericanSociety
ofMechanicalEngineers(ASME)in1997,theEnergySystemsAwardandthe
PendrayLiteratureAwardoftheAIAAin1999and2004,respectively,andsev-
eralawardsforbestconferencepapers.HeisanoriginalmemberoftheHighly
CitedResearchersdatabaseoftheInstituteforScientificInformation(ISI).
Professor Law is a former president of the Combustion Institute, a Fellow
oftheAIAAandtheASME,andamemberoftheU.S.NationalAcademyof
Engineering.
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COMBUSTION
PHYSICS
CHUNG K. LAW
PrincetonUniversity
iii
cambridge university press
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo
Cambridge University Press
TheEdinburghBuilding,Cambridgecb22ru,UK
Published in the United States of America by Cambridge University Press, New York
www.cambridge.org
Information on this title: www.cambridge.org/9780521870528
© Chung K. Law 2006
This publication is in copyright. Subject to statutory exception and to the provision of
relevant collective licensing agreements, no reproduction of any part may take place
without the written permission of Cambridge University Press.
First published in print format 2006
isbn-13 978-0-511-24584-8eBook (EBL)
isbn-10 0-511-24584-XeBook (EBL)
isbn-13 978-0-521-87052-8hardback
isbn-10 0-521-87052-6 hardback
Cambridge University Press has no responsibility for the persistence or accuracy of urls
for external or third-party internet websites referred to in this publication, and does not
guaranteethatanycontentonsuchwebsitesis,orwillremain,accurateorappropriate.
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TomywifeHelen
andtoourchildren
Jonathan,Jennifer,andJeffrey
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Contents
Preface pagexvii
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
0.1. MajorAreasofCombustionApplication 1
0.2. ScientificDisciplinesComprisingCombustion 6
0.3. ClassificationsofFundamentalCombustionPhenomena 7
0.4. OrganizationoftheText 10
0.5. LiteratureSources 12
1. CHEMICALTHERMODYNAMICS . . . . . . . . . . . . . . . . . . . . . . . . 14
1.1. PracticalReactantsandStoichiometry 14
1.1.1. PracticalReactants 14
1.1.2. Stoichiometry 15
1.2. ChemicalEquilibrium 16
1.2.1. FirstandSecondLaws 16
1.2.2. ThermodynamicFunctions 16
1.2.3. CriterionforChemicalEquilibrium 18
1.2.4. PhaseEquilibrium 18
1.2.5. EquilibriumConstants 21
1.2.6. EquilibriumConstantsinthePresenceofCondensedPhases 22
1.2.7. MultipleReactions 24
1.2.8. ElementConservation 24
1.2.9. RestrictedEquilibrium 25
1.3. EquilibriumCompositionCalculations 26
1.3.1. EquilibriumCompositionofHydrocarbon–AirMixtures 26
1.3.2. TheMajor–MinorSpeciesModel 28
1.3.3. ComputerSolutions 30
1.4. EnergyConservation 31
1.4.1. HeatsofFormation,Reaction,andCombustion 31
1.4.2. EstimationofHeatofReactionfromBondEnergies 34
1.4.3. DeterminationofHeatofReactionfromK (T) 35
p
1.4.4. SensibleEnergiesandHeatCapacities 35
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viii Contents
1.4.5. EnergyConservationinAdiabaticChemicalSystems 37
1.4.6. AdiabaticFlameTemperatureandEquilibriumComposition 37
PROBLEMS 49
2. CHEMICALKINETICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2.1. PhenomenologicalLawofReactionRates 52
2.1.1. TheLawofMassAction 52
2.1.2. ReversibleReactions 53
2.1.3. MultistepReactions 54
2.1.4. Steady-StateApproximation 54
2.1.5. PartialEquilibriumApproximation 55
2.1.6. ApproximationsbyGlobalandSemiglobalReactions 56
2.1.7. ReactionOrderandMolecularity 57
2.2. TheoriesofReactionRates:BasicConcepts 58
2.2.1. TheArrheniusLaw 58
2.2.2. TheActivationEnergy 59
2.2.3. CollisionTheoryofReactionRates 62
2.2.4. TransitionStateTheoryofReactionRates 64
2.3. TheoriesofReactionRates:UnimolecularReactions 67
2.3.1. LindemannTheory 68
2.3.2. Rice–Ramsperger–Kassel(RRK)Theory 70
2.3.3. RepresentationofUnimolecularReactionRateConstants 71
2.3.4. ChemicallyActivatedReactions 72
2.4. ChainReactionMechanisms 74
2.4.1. Straight-ChainReactions:TheHydrogen–HalogenSystem 74
2.4.2. Branched-ChainReactions 76
2.4.3. FlameInhibitors 79
2.5. ExperimentalandComputationalTechniques 80
PROBLEMS 81
3. OXIDATIONMECHANISMSOFFUELS . . . . . . . . . . . . . . . . . . . . . 84
3.1. PracticalFuels 85
3.2. OxidationofHydrogenandCarbonMonoxide 89
3.2.1. ExplosionLimitsofHydrogen–OxygenMixtures 89
3.2.2. CarbonMonoxideOxidation 94
3.2.3. InitiationReactionsinFlames 94
3.3. OxidationofMethane 95
3.3.1. GeneralConsiderationsofHydrocarbonOxidation 95
3.3.2. MethaneAutoignition 96
3.3.3. MethaneFlames 99
3.4. OxidationofC Hydrocarbons 100
2
3.5. OxidationofAlcohols 102
3.6. High-TemperatureOxidationofHigherAliphaticFuels 103
3.6.1. Theβ-ScissionRule 104
3.6.2. OxidationMechanisms 106
3.7. OxidationofAromatics 109
