Thermal conductivity of a material is a measure of its ability to a particular material conduct heat. In the international system of units (SI), thermal conductivity is measured in watts per meter-kelvin (W/(m.K)). In imperial units, thermal conductivity is measured in BTU/(h·ft·oF).
Thermal Conductivity of Solids
Solid composition, shape, structure all affect how well it conduct heat. Many handbooks provide thermal conductivity of solids for frequently used engineering materials.
Thermal Conductivity of Liquid
Equation below can be used to estimate thermal conductivity of liquid.
Where:
k = thermal conductivity (W/(moC))
M = molecular weight
Cp = specific heat capacity (kJ/(kgoC))
ρ = density (kg/m3)
Example
Estimate the thermal conductivity of benzene at 30oC.
Solution
Density of benzene at 30oC = 875 kg/m3
Molecular weight of benzene = 78
Specific heat of benzene = 1.75 kJ/(kgoC)
Therefore, thermal conductivity:
Thermal conductivity = 0.12 W/(moC)
Therefore, the density of benzene at 30oC is estimated 0.12 W/(moC). This value is closed to the experiment in known handbooks, which is 0.16 W/(moC).
Reference:
Sinnot, R.K., Chemical Engineering Design Volume 6 Fourth Edition, Elsevier Butterworth-Heinemann, 2005.