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Article: A model for stripping multicomponent vapor from unsaturated soil with free and trapped residual nonaqueous phase liquid

TitleA model for stripping multicomponent vapor from unsaturated soil with free and trapped residual nonaqueous phase liquid
Authors
Issue Date1999
PublisherAmerican Geophysical Union.
Citation
Water Resources Research, 1999, v. 35 n. 2, p. 385-340 How to Cite?
AbstractWe present a model for the multicomponent vapor transport due to air venting in an unsaturated zone in the presence of free and trapped phases of residual nonaqueous phase liquid (NAPL). On the microscale the soil particles are assumed to form spherical aggregates with micropores filled with-immobile water, trapped phases of NAPL and air. The interaggregate space is occupied with mobile air, and a thin film of free NAPL adheres on the aggregate surface. While the free NAPL can readily be in equilibrium with macropore vapor, the mass transfer from immobile phases inaggregates is rate-limited by aqueous diffusion. This model enables us to predict the vapor concentrations of various chemical species and the free NAPL saturation over the macroscale, based on the detailed understanding of the aqueous concentrations of the species and the trapped NAPL saturation within the aggregates. The model is compared favorably with some experimental data of sparging multicomponent vapor out of an intact core taken from a contaminated site. The distinctive features of multicomponent transport, clearly exhibited by the data, are further examined in the simulations of a hypothetical case of three-aromatic vapor transport under a radial flow field. It is found that while the vapor concentration of the most volatile component drops monotonically with time, those of the less volatile may rise as their mole fractions in the NAPL increase. The vapor concentration of a heavy component may have a local maximum at the evaporation front of the free NAPL. In the case of radial flow the free NAPL has two receding evaporation fronts. Condensation of the heavy component downstream of the far front causes a temporary increase of its total concentration there. With trapped NAPL and soil aggregation the macroscale transport is retarded, and the effluent concentrations end up in noticeable tailing.
Persistent Identifierhttp://hdl.handle.net/10722/75635
ISSN
2015 Impact Factor: 3.792
2015 SCImago Journal Rankings: 2.661
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorNg, COen_HK
dc.contributor.authorMei, CCen_HK
dc.contributor.authorOstendorf, DWen_HK
dc.date.accessioned2010-09-06T07:13:05Z-
dc.date.available2010-09-06T07:13:05Z-
dc.date.issued1999en_HK
dc.identifier.citationWater Resources Research, 1999, v. 35 n. 2, p. 385-340en_HK
dc.identifier.issn0043-1397en_HK
dc.identifier.urihttp://hdl.handle.net/10722/75635-
dc.description.abstractWe present a model for the multicomponent vapor transport due to air venting in an unsaturated zone in the presence of free and trapped phases of residual nonaqueous phase liquid (NAPL). On the microscale the soil particles are assumed to form spherical aggregates with micropores filled with-immobile water, trapped phases of NAPL and air. The interaggregate space is occupied with mobile air, and a thin film of free NAPL adheres on the aggregate surface. While the free NAPL can readily be in equilibrium with macropore vapor, the mass transfer from immobile phases inaggregates is rate-limited by aqueous diffusion. This model enables us to predict the vapor concentrations of various chemical species and the free NAPL saturation over the macroscale, based on the detailed understanding of the aqueous concentrations of the species and the trapped NAPL saturation within the aggregates. The model is compared favorably with some experimental data of sparging multicomponent vapor out of an intact core taken from a contaminated site. The distinctive features of multicomponent transport, clearly exhibited by the data, are further examined in the simulations of a hypothetical case of three-aromatic vapor transport under a radial flow field. It is found that while the vapor concentration of the most volatile component drops monotonically with time, those of the less volatile may rise as their mole fractions in the NAPL increase. The vapor concentration of a heavy component may have a local maximum at the evaporation front of the free NAPL. In the case of radial flow the free NAPL has two receding evaporation fronts. Condensation of the heavy component downstream of the far front causes a temporary increase of its total concentration there. With trapped NAPL and soil aggregation the macroscale transport is retarded, and the effluent concentrations end up in noticeable tailing.en_HK
dc.languageengen_HK
dc.publisherAmerican Geophysical Union.en_HK
dc.relation.ispartofWater Resources Researchen_HK
dc.rightsWater Resources Research. Copyright © American Geophysical Union.en_HK
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.titleA model for stripping multicomponent vapor from unsaturated soil with free and trapped residual nonaqueous phase liquiden_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0043-1397&volume=35&issue=2&spage=385&epage=406&date=1999&atitle=A+model+for+stripping+multicomponent+vapor+from+unsaturated+soil+with+free+and+trapped+residual+nonaqueous+phase+liquiden_HK
dc.identifier.emailNg, CO:cong@hku.hken_HK
dc.identifier.authorityNg, CO=rp00224en_HK
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1029/98WR02166en_HK
dc.identifier.scopuseid_2-s2.0-0032917477en_HK
dc.identifier.hkuros41052en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0032917477&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume35en_HK
dc.identifier.issue2en_HK
dc.identifier.spage385en_HK
dc.identifier.epage340en_HK
dc.identifier.isiWOS:000078220800004-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridNg, CO=7401705594en_HK
dc.identifier.scopusauthoridMei, CC=35299759800en_HK
dc.identifier.scopusauthoridOstendorf, DW=7004460309en_HK

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