Study of Thermal Conductivity of Soils for Varying Density and Water Content Profiles

In Analytical Theory of Heat, 1822 Joseph Fourier stated, “The problem of terrestrial temperatures presents one of the most beautiful applications of the theory of heat.” The experimental schedule is planned so as to study a wide variety of artificially mixed soil using naturally available single component soils, i.e., sand, silt, and single mineral clay (kaolinite), to remove heterogeneity due to variation of various minerals in naturally occurring soils for the thermal conductivity as measured in laboratory setup, on the basis of physical properties of the soil. The objectives of this investigation of the thermal conductivity of soils are to employ the thermal probe method to obtain reliable thermal conductivity data for different local natural soils. For evaluating the radial flow of the heat, the soil is compacted in porcelain pipes. It has thermocouple controlled vertical heater rod placed at the center as source and 20 thermocouples placed radially in four directions perpendicular in plan for temperature profile readings. The second setup fabricated in house was aimed at studying the flow of thermal energy in longitudinal direction as well as with depth for which a rectangular steel tank was fabricated. The heat source was placed at one end of the tank, whereas the thermocouples were placed all along the length and a second row placed at different depths along the length. The influence of soil properties such as water content, dry density, and porosity on thermal conductivity is also observed.