What Is Thermal Effusivity? What’s The Difference From Thermal Conductivity?
Thermal Effusivity, is a value to describe the behavior of the heat storing or dissipating capability of materials. It is the square root of the product of the material's thermal conductivity and its volumetric heat capacity:
√ Kρcp
K: Thermal Conductivity (W / m⋅K)
ρ: Density (kg/m2)
cp: Specific Heat Capacity (J / kg⋅K)
Thermal effusivity is used to describe heat transition behavior of two objects, when the two objects are contacted to each other. When the two materials have the same thermal effusivity, the heat transition behavior will equal to a unique object as if there are no junction between the two objects.
A typical example is the human skin. When we touch different materials for a period, we will have different feelings. We feel cool with some materials, and feel warm with some others. Let's say, hand on a metal pipe in the park, we feel cool, and a cotton cloth is warm. To the physical measurement, the metal pipe has higher thermal effusivity and the cotton cloth is lower. Thermal effusivity is a unit which can express the real physical amount, instead of the feeling of ‘cooler’ or ‘warmer’.
The traditional thermal conductivity analyzer needs a series of calculations to get the thermal effusivity, and even the thermal conductivity need to be calculated from the thermal resistance value, which the known density and specific heat capacity. Typically, these thermal conductivity analyzer takes a long time to get the final conductivity and effusivity.
TCi, an advanced thermal conductivity analyzer, which is based on the latest measurement technology, MTPS (Modified Transient Plane Source). In a few minutes, one can get the thermal conductivity result and thermal effusivity result directly, without any conversion. In addition, due to the special design of the sensor and heater, so TCi thermal conductivity analyzer can accept the most diverse sample form, either flake, block, powder, solid, liquid samples, can be directly measured thermal conductivity value.
TCi accepts versatile forms of materials, include, solids, liquids, powders and pastes and have the flexibility to operate in various environmental enclosures. Besides, TCI has various accessories to simulate different environment conditions, such as press kit, which can simulate the material at in different compression force and one can measure the conductivity and effusivity versus the degree of pressing.
ACTTR Technology presents the entire product line of C-Therm in Taiwan. If you’re interested in surveying more details about C-Therm product, you’re welcome to contact ACTTR!