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An Electrical Model of Heat Flow in Soil
Author(s) -
Guaraglia Dardo O.,
Pousa Jorge L.
Publication year - 1999
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/sssaj1999.03615995006300030006x
Subject(s) - thermal conduction , mechanics , thermal resistance , materials science , thermal conductivity , electrical resistance and conductance , electrical conductor , thermal , flow (mathematics) , capacitor , soil thermal properties , heat transfer , voltage , electrical engineering , soil water , thermodynamics , physics , composite material , engineering , geology , soil science , field capacity
Abstract Heat diffusing away from a cylindrical heater embedded in soil with volumetric heat capacity ρc and thermal conductivity λ is modeled analogically and solved using available electrical circuit analysis software. Soil is considered to be divided into a series of heater‐centered, cylindrical layers of carefully chosen thicknesses whose thermal resistances and capacitances can be represented by a ladder of variable electrical resistances and capacitances that are connected to a current source which represents heat flow. Starting from the basic analogy between heat flow in soil and current flow in an electrical transmission line of given distributed parameters, the modeling circuit was applied to heaters of cylindrical geometry and different sizes. The circuit was modified to account for finite probe‐length effects and the thermal characteristics of the heater. Finite probe‐length effects were modeled by enlarging the basic cylindrical diffusion layers at both ends. The thermal characteristics of the heater were represented with a ladder of variable electrical resistances and capacitances connected to the current source. The surrounding soil beyond the last cylindrical layer was modeled by a pure resistance through which capacitors finally discharge, thus representing heat diffusing farther into the soil. Model results compare well with the analytical solution for radial conduction of a short‐duration heat pulse and with laboratory measurements carried out with sand. The simplicity, advantages, and range of applications of the electrical model are exposed briefly.