What is thermal diffusivity? Thermal diffusivity (SI derived unit of mm2/s) is a combination of physical properties (conductivity, density and specific heat capacity). In heat transfer analysis, the thermal conductivity is divided by density and specific heat capacity at constant pressure. It measures the rate of transfer of heat of a material from the hot side to the cold side. The formula of thermal diffusivity is:
α = k / ρcρ
where:
α is the thermal diffusivity
k is thermal conductivity (W /(m•K))
ρ is the density (kg/m³)
cρ is the specific heat capacity (J/(kg•K))
In a substance with high thermal diffusivity, heat moves rapidly through it because the substance conducts heat quickly relative to its volumetric heat capacity.
Available Thermal Diffusivity Testing Methods
Thermal Diffusivity Testing can be done in different methods such as using transient plane source, laser flash apparatus or even transient hot wire method.
Transient Plane Source
Transient Measurement of Thermal Diffusivity have been performed using the Hot Disk TPS method with sensors in thin samples of metallic materials.
Laser Flash Method
The thermal diffusivity measurement often done using the Laser Flash Apparatus (LFA). It involves heating a strip or cylindrical sample with a short energy pulse at one end and analyzing the temperature.
Transient Hot Wire
The transient Hot Wire method is used for the measurement of thermal diffusivity of liquids and pastes. With an appropriate design of the instruments such as the liquid thermal conductivity meter THW-L2, measurements of fluid thermal diffusivity can be made with reasonable accuracy over wide ranges of density.
For accurate testing, contact thermest
Reference:
https://en.wikipedia.org/wiki/Thermal_diffusivity
