Particle-fluid mass transfer in multiparticle systems at low Reynolds numbers (Articolo in rivista)

Type
Label
  • Particle-fluid mass transfer in multiparticle systems at low Reynolds numbers (Articolo in rivista) (literal)
Anno
  • 2013-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1016/j.ces.2013.01.012 (literal)
Alternative label
  • F. Scala (2013)
    Particle-fluid mass transfer in multiparticle systems at low Reynolds numbers
    in Chemical engineering science
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • F. Scala (literal)
Pagina inizio
  • 90 (literal)
Pagina fine
  • 101 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 91 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Istituto di ricerche sulla combustione - CNR (literal)
Titolo
  • Particle-fluid mass transfer in multiparticle systems at low Reynolds numbers (literal)
Abstract
  • The problemofmasstransferbetweenactivesolidparticlesandafluidinmultiparticlesystemsis examinedwithafocusonthestagnantandthelowReynoldsnumbercases.Thisproblemhasattracted significantattentionwithregardtooperationoffixedandfluidizedbeds.Itisrecognizedthatdifferent Sherwoodnumberscanbedefineddependingonthechoiceofthereferenceconcentrationdifference (drivingforce).Aneffective Sh has oftenbeenusedtoanalyzeexperimentaldatabasedonanoverall concentrationdifferenceacrossthebed.Alocal Sh can alsobeintroducedbasedonaconcentration differenceclosetotheactiveparticle.However,theuseofthesetwodifferentSherwoodnumbers impliesadifferentimplementationofthemassbalanceequations. The massbalanceequationsarehereanalyticallysolvedbothunderstagnantandnon-stagnant conditionsinamultiparticlesystemundersuitablesimplifyingassumptions.Equationsfortheeffective and localSherwoodnumbersarederivedforthegeneralcaseandfortheasymptoticlimits.Allowance is givenforthevariationofbedvoidageandvolumefractionofactiveparticlesinthebed.Itisshown that thelocal Sh only dependsongeometricalandfluid-dynamicsconsiderationsandaccordinglyhasa generalvalidity.Onthecontrary,theeffective Sh also dependsontheassumptionsmadeinderivingthe mass balanceequationsacrossthebed(e.g.,fluidplugflow).Theuseofthelocal Sh is therefore suggested. Resultsshowthatfor Re-0 thelimitingvalueofthelocal Sh is alwaysafinitenumber,whilethe effective Sh tendstozerolinearlywith Re. Itisshownthatthisresultissimplyaconsequenceofthe plug flowassumptionmadeinthebedmassbalance.Thegeneralexpressionsderivedherecompare very welltoexperimentaltrendsforthecasesoflargeReynoldsnumbersandoffewisolatedactive spheres immersedinabedofinertparticles,wheremostofthereportedexperimentaldatagather. Unfortunately,forthemostcontroversialcaseofverylow Re in bedsmadeentirelyofactiveparticlesno reliabledataappearstobeavailabletochecktheaccuracyoftheexpressions. (literal)
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