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1、CombustionandFlame133(2003)107–117Approximationstothedistributedactivationenergymodelforthepyrolysisofcoalab,cC.P.Please,M.J.McGuinness*,D.L.S.McElwainaDepartmentofMathematics,UniversityofSouthampton,Southampton,UKSO171BJbSchoolofMathematicalandComputingSciences,VictoriaUniversityofWellingt
2、on,POBox600,Wellington,NewZealandcSchoolofMathematicalSciences,QueenslandUniversityofTechnology,GPOBox2434,BrisbaneQ4001,AustraliaReceived23April2002;receivedinrevisedform18November2002;accepted22November2002AbstractTheDistributedActivationEnergyModel(DAEM),usedforthepyrolysisofarangeofmate
3、rials(includingcoal,biomass,residualoilsandkerogen),assumesthatthethermaldecompositionofnumerouscomponentsisdescribedbyadistributionofactivationenergies.Existingtheoriesarereviewedwithparticularfocusonmethodsusedtoevaluatesolutionsquicklyandefficiently.Thispaperdemonstratesthatpreviousapproa
4、chestakentosimplifythemethodsofsolutioncanusuallybeidentifiedasbelongingtooneoftwodistinctandphysicallyrelevantregimes.Acarefulanalysisinthesetworegimesisgivenbaseduponasymptoticexpansions,leadingtosystematicmethodsforrapidlyfindingaccurateapproximations.Thenewtheoryresultsinsimpleexpressions
5、forthedevolatilisationrateofagivendistributionofreactants.Themethodtherebyprovidesarapidandhighlyeffectivemethodforestimatingkineticparametersandthedistributionofactivationenergies.Comparisonofthesimplifiedresultswithexistingtheoriesandwithcalculationsofthefullmodelaregiven.Themethodsprovide
6、ausefulbasisforcalculationsofcoupledmodelsofvolatilisationandcombustion,andformodelswithspatiallyvaryingtemperatures.©2003TheCombustionInstitute.Allrightsreserved.Keywords:Coalvolatilization;Fastevaluation;Asymptoticanalysis;Inverseproblemdoubleintegrals,involvingrapidlyvaryingfunctions1.In
7、troductionandthiscreatessignificantnumericaldifficulties.TheaimofthispaperistouseasymptoticmethodstoThedistributedactivationenergymodel(DAEM)makeaccurateapproximationstotheintegralsandhasprovedverysuccessfulindescribingthepyroly-therebyallowrapidsolutions.