Glossary of Terms
Thermal Effusivity
Thermal effusivity of a material is defined as the square root of the product of the material’s thermal conductivity and its volumetric heat capacity.
e = √k∙ρ∙Cρ
A material’s thermal effusivity is a measure of its ability to exchange thermal energy with its surroundings. Although, the quantity can be expressed in bulk property terms, it is not measured in bulk property terms. If material is not a solid, then other heat transfer mechanisms exist, modifying the “k” expressed in thermal effusivity to thermal conductance.
Thermal Effusance
Thermal Effusance of a material is defined as the square root of the product of the material’s thermal condustance and its volumetric heat capacity.
e = √k∙ρ∙Cρ
A material’s thermal effusance is a measure of its ability to exchange thermal energy with its surroundings, when the heat transfer mechanism is not thermal conductivity, typically found in measurement of a non-solid.