Thermal conductivity (λ) and thermal resistivity (ρ) are related but opposite properties of soil. Thermal conductivity measures the ability of soil to conduct heat, while thermal resistivity measures the ability of soil to resist heat flow.
The relationship between thermal conductivity and thermal resistivity is inverse:
λ = 1/ρ
or
ρ = 1/λ
In other words, as thermal conductivity increases, thermal resistivity decreases, and vice versa.
Thermal conductivity (λ) is typically measured in units of Watts per meter-Kelvin (W/m·K), while thermal resistivity (ρ) is measured in units of meter-Kelvin per Watt (m·K/W).
Soil's thermal conductivity and resistivity depend on factors like moisture content, density, mineral composition, and temperature. Understanding these properties is crucial in geotechnical engineering, environmental science, and heat transfer applications.
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The parameter k is a transport property known as the thermal conductivity
(W/m . K) and is a characteristic of the material.
an analogy exists between the diffusion of heat and electrical charge. Just as an electrical resistance(Re) is associated with the conduction of electricity,a thermal resistance may be associated with the conduction of heat. Defining resistance as the ratio of a driving potential to the corresponding transfer rate.
for example this analogy:
thermal resistance for conduction in a plane wall is Rt,cond=deltaT/q=L/KA
Similarly, for electrical conduction in the same system, Ohm’s law provides an electrical resistance of the form Re=E1-E2/I=L/σA.or I=V/Re.