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Method for Maintaining One‐Dimensional Temperature Gradients in Unsaturated, Closed Soil Cells
Author(s) -
Zhou J.,
Heitman J. L.,
Horton R.,
Ren T.,
Ochsner T. E.,
Prunty L.,
Ewing R. P.,
Sauer T. J.
Publication year - 2006
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2005.0336n
Subject(s) - temperature gradient , heat exchanger , materials science , volume (thermodynamics) , environmental science , steady state (chemistry) , mechanics , soil science , chemistry , thermodynamics , meteorology , physics
One‐dimensional temperature gradients are difficult to achieve in nonisothermal laboratory studies because, in addition to desired axial temperature gradients, ambient temperature interference (ATI) creates a radial temperature distribution. Our objective was to develop a closed soil cell with limited ATI. The cell consists of a smaller soil column, the control volume, surrounded by a larger soil column, which provides radial insulation. End boundary temperatures are controlled by a new spiral‐circulation heat exchanger. Four cell size configurations were tested for ATI under varying ambient temperatures. Results indicate that cells with a 9‐cm inner column diameter, 5‐cm concentric soil buffer, and either 10‐ or 20‐cm length effectively achieved one‐dimensional temperature conditions. At 30°C ambient temperature, and with axial temperature gradients as large as 1°C cm −1 , average steady‐state radial temperature gradients in the inner soil columns were <0.02°C cm −1 Thus, these cell configurations meet the goal of maintaining a one‐dimensional temperature distribution. These cells provide new opportunities for improving the study of coupled heat and water movement in soil.