In thermodynamics, the thermal effusivity, thermal inertia or thermal responsivity of a material is defined as the square root of the product of the material's thermal conductivity and its volumetric heat capacity.
A material's thermal effusivity is a measure of its ability to exchange thermal energy with its surroundings.
This expression is valid for all times for semi-infinite bodies in perfect thermal contact. It is also a good first guess for the initial contact temperature for finite bodies.
Direct measurement of thermal effusivity may be performed using specialty sensors, as pictured.
- i.e. their thermal capacity is sufficiently large that their temperatures will not change measurably owing to this heat transfer
- A reference defining various thermal properties[dead link]
- Williams, F. A. (2009). "Simplified theory for ignition times of hypergolic gelled propellants". J. Propulsion and Power. 25 (6): 1354–1357. doi:10.2514/1.46531.
- Baehr, H.D.; Stephan, K. (2004). Wärme- und Stoffübertragung 4. Auflage. Springer. p. 172. doi:10.1007/978-3-662-10833-8. ISBN 978-3-662-10834-5.
- "Thermal heat transfer". HyperPhysics.