Behavior of Moist Soils in a Thermal Energy Field

Abstract

AbstractAn account is given of the soil thermal resistivity problem faced by the electric power industry and its co-operative engineering solution. Data obtained in this activity and collected from other sources are employed to check the validity of various concepts that hare been developed to explain the phenomena observed when soils, composed of solid, liquid and gaseous phases, are placed in a thermal energy field. It is shown that formulas based on simple parallel or series arrangement of the component phases cannot account for the actual thermal transmission properties of moist soils. Nor can any one of the moisture transfer mechanisms, that have been proposed in explanation of the water movement associated with heat conduction in moist soils, by itself account for the observed magnitudes of thermal conductivity. Analysis of pertinent data renders it very probable that both evaporation-condensation and oriented film mechanisms must be involved in the coupled heat and moisture transport. What really takes place is an intricate interaction of a number of different events that can be understood qualitatively on the basis of the best available knowledge of soil-water interaction and its temperature dependence. Much work, however, remains to be done before a quantitative understanding can even be approached. The nature and magnitude of the remaining scientific problem can be appraised from the following pertinent statement by Szent-György. (1958) “The complexity of the situation with its very subtle equilibria makes conditions most colorful and begins to resemble the subtle complexity which characterizes life.”