Definition of Thermal Diffusivity

Thermal DiffusivityThermal diffusivity (a with the unit mm2/s) is a material-specific property for characterizing unsteady heat conduction. This value describes how quickly a material reacts to a change in temperature.Thermal diffusivity (a with the unit mm2/s) is a material-specific property for characterizing unsteady heat conduction. This value describes how quickly a material reacts to a change in temperature.

In order to predict cooling processes or to simulate temperature fields, the Thermal DiffusivityThermal diffusivity (a with the unit mm2/s) is a material-specific property for characterizing unsteady heat conduction. This value describes how quickly a material reacts to a change in temperature.thermal diffusivity must be known; it is a requisite for solving the Fourier Differential Equation for unsteady heat conduction.

An overview of 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 and thermal diffusivity values of selected materials is shown in table 1.

Source: www.chemie.de/lexikon
Information about the thermal conductivity of further materials can be found in the “Thermal Properties of Elements", "Thermal Properties of Ceramics" and "Thermal Properties of Polymers” posters.

The thermal diffusivity can be measured by LFA.

MaterialThermal 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 / W/(m•K)Thermal DiffusivityThermal diffusivity (a with the unit mm2/s) is a material-specific property for characterizing unsteady heat conduction. This value describes how quickly a material reacts to a change in temperature.Thermal Diffusivity / mm2/s
Aluminum23798.8
Steel8122.8
Copper399117
Fused Silica1.400.87
Gypsum0.510.47
Polyethylene0.350.15
Marble2.81.35

Table 1: Thermal conductivity and thermal diffusivity values for various materials