Glossary

Thermal Diffusivity

Definition of Thermal Diffusivity

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 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 our posters “Thermal Properties of Elements", "Thermal Properties of Ceramics" and "Thermal Properties of Polymers”.

The thermal diffusivity can be measured by LFA.

 

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

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 Diffusivity / mm2/s
Aluminum23798.8
Steel8122.8
Copper399117
Fused Silica1.400.87
Gypsum0.510.47
Polyethylene0.350.15
Marble2.81.35