Definition of Thermal Resistance
The absolute thermal resistance, R, is a property of a material property that describe ing how easily or difficultly heat can flow through a material. It is defined as the temperature difference, ΔT, across a material divided by the rate of heat transfer, dQ / dt = Q̇, through the material, and has the unit of Kelvin per Watt [K/W].
The specific thermal resistance, R [(m2K)/W], depends on the thickness, d, and the Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity, λ, of a material.
The higher the thermal resistance, the better the insulation properties. The thermal resistant is measured by means of HFM and GHP and can also be calculated from LFA results.