An analysis of a mixed convection associated with thermal heating in contaminated porous media

Magdalena M. Krol, Richard Johnson, Brent E. Sleep

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The occurrence of subsurface buoyant flow during thermal remediation was investigated using a two dimensional electro-thermal model (ETM). The model incorporated electrical current flow associated with electrical resistance heating, energy and mass transport, and density dependent water flow. The model was used to examine the effects of heating on sixteen subsurface scenarios with different applied groundwater fluxes and soil permeabilities. The results were analyzed in terms of the ratio of Rayleigh to thermal Peclet numbers (the buoyancy ratio). It was found that when the buoyancy number was greater than unity and the soil permeability greater than 10-12m2, buoyant flow and contaminant transport were significant. The effects of low permeability layers and electrode placement on heat and mass transport were also investigated. Heating under a clay layer led to flow stagnation zones resulting in the accumulation of contaminant mass and transport into the low permeability layer. The results of this study can be used to develop dimensionless number-based guidelines for site management during subsurface thermal activities.

Original languageEnglish (US)
Pages (from-to)7-17
Number of pages11
JournalScience of the Total Environment
Volume499
DOIs
StatePublished - Nov 5 2014

Fingerprint

Convection
Mixed convection
Heating
Porous materials
porous medium
Hot Temperature
convection
permeability
Permeability
heating
mass transport
buoyancy
Buoyancy
stagnation flow
dimensionless number
Soil
Mass transfer
Impurities
pollutant transport
Soils

Keywords

  • Buoyancy ratio
  • Contaminant transport
  • Peclet number
  • Rayleigh number
  • Thermal remediation

ASJC Scopus subject areas

  • Environmental Chemistry
  • Pollution
  • Waste Management and Disposal
  • Environmental Engineering
  • Medicine(all)

Cite this

An analysis of a mixed convection associated with thermal heating in contaminated porous media. / Krol, Magdalena M.; Johnson, Richard; Sleep, Brent E.

In: Science of the Total Environment, Vol. 499, 05.11.2014, p. 7-17.

Research output: Contribution to journalArticle

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AB - The occurrence of subsurface buoyant flow during thermal remediation was investigated using a two dimensional electro-thermal model (ETM). The model incorporated electrical current flow associated with electrical resistance heating, energy and mass transport, and density dependent water flow. The model was used to examine the effects of heating on sixteen subsurface scenarios with different applied groundwater fluxes and soil permeabilities. The results were analyzed in terms of the ratio of Rayleigh to thermal Peclet numbers (the buoyancy ratio). It was found that when the buoyancy number was greater than unity and the soil permeability greater than 10-12m2, buoyant flow and contaminant transport were significant. The effects of low permeability layers and electrode placement on heat and mass transport were also investigated. Heating under a clay layer led to flow stagnation zones resulting in the accumulation of contaminant mass and transport into the low permeability layer. The results of this study can be used to develop dimensionless number-based guidelines for site management during subsurface thermal activities.

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