Temperature dependent thermal diffusivity using PDE Toolbox (2024)

FAQs

How is thermal diffusivity dependent on temperature? ›

It was found that the thermal diffusivity decreased with an increasing temperature [2,8], wet materials had a higher thermal diffusivity, and the thermal diffusivity was a minimum at the α−β transition [2].

The most effective method used for measuring thermal diffusivity is the flash method. This transient technique features short measurement times, is completely non-destructive, and provides values with excellent accuracy and reproducibility.

Thermal diffusivity is important because it can tell how fast or slow a material can heat up. High values of thermal diffusivity mean a lower heat diffusion rate. Thus, the material can heat up or cool down quickly. Whereas a lower thermal diffusivity value means a higher heat diffusion rate.

The thermal diffusivity equation is α = k/ρcp, where α represents thermal diffusivity, k is thermal conductivity, ρ is density, and cp is specific heat capacity. This equation allows one to understand how quickly a material can transmit temperature changes.

The greater the temperature of the system, the greater the kinetic energy of the atoms, therefore temperature has a significant effect on the diffusivity of the species.

Diffusion is directly proportional to temperature as it increases the kinetic energy of the molecules and inversely proportional to density of the substance. On increasing the temperature, the diffusion increases and on increasing the density of substance, the diffusion decreases and vice versa.

Thermal diffusivity is defined as the ratio of thermal conductivity to density and specific heat capacity at constant pressure and can be obtained by the following equation: (17) K = k / ρ c p . It describes the ability of a material to conduct thermal energy relative to its ability to store thermal energy [180].

thermal conductivity, κ, is how well the material passes on heat (thermal energy), while. thermal diffusivity, α, is how well the material passes on a temperature change.

Is thermal diffusivity more for liquid or gas? ›

Generally, gases have low volumetric heat capacity (due to very low density) which leads to greater thermal diffusivity.

Temperature: Higher temperatures increase the energy and therefore the movement of the molecules, increasing the rate of diffusion. Lower temperatures decrease the energy of the molecules, thus decreasing the rate of diffusion.

It was found that the thermal diffusivity decreased with an increasing temperature [2,8], wet materials had a higher thermal diffusivity, and the thermal diffusivity was a minimum at the α−β transition [2].

Thermal Diffusivity is often measured with the flash method (LFA). It can also be measured with Hot Disc Transient Plane Source (TPS), Transient Hot Wire (THW) and Monotonic Heating (MMH). Our thermal diffusivity measurement methods cover a wide range of temperature and sample types.

It is directly proportional to thermal conductivity.

Temperature: Higher temperatures increase the energy and therefore the movement of the molecules, increasing the rate of diffusion. Lower temperatures decrease the energy of the molecules, thus decreasing the rate of diffusion.

It is directly proportional to thermal conductivity.

Diffusivity can be defined as the ability of a drug to diffuse through the membrane and is inversely related to the molecular size. Diffusivity also depends on size and shape of the cavities of the membrane.

As temperature increases, the thermal conductivity of metals generally decreases because, at higher temperatures, the increased phonon scattering (vibrations within the lattice structure) reduces the mean free path of electrons, thereby decreasing thermal conductivity.