Thermal diffusivity

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In heat transfer analysis, thermal diffusivity is the thermal conductivity divided by density and specific heat capacity at constant pressure. It measures the rate of transfer of heat of a material from the hot end to the cold end. It has the SI derived unit of m2/s. Thermal diffusivity is usually denoted by α but a, h, κ (kappa), and D are also used.

The formula is:

α = k /(ρ·cp)

where

Together, ρ·cp can be considered the volumetric heat capacity (J/(m3·K)).

Thermal diffusivity is often measured with the flash method. It involves heating a strip or cylindrical sample with a short energy pulse at one end and analyzing the temperature change (reduction in amplitude and phase shift of the pulse) a short distance away.

References

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