Thermal diffusivity

Thermal diffusivity measures how quickly temperature variations spread through a material. It equals thermal conductivity divided by volumetric heat capacity.

Heat equation: A partial differential equation describing how temperature or another diffusing quantity changes over space and time. Thermal diffusivity is the coefficient multiplying the spatial temperature-curvature term.
Heat capacity: The amount of heat needed to raise an object's temperature by one degree. The volumetric form of heat capacity is diffusivity's heat-storage denominator.
Thermal diffusivity measurement: Experimental determination of a material's rate of thermal diffusion. Transient heating methods infer diffusivity from the observed temperature response.
Thermal resistance: A measure of opposition to heat flow between two locations or across a component. Resistance describes steady heat-flow difficulty, not the pace of transient temperature spreading.
Volumetric heat capacity: The heat required to raise the temperature of a unit volume of material by one degree. It appears in the denominator, measuring resistance to temperature change through heat storage.
Specific heat capacity: The heat required to raise the temperature of a unit mass of a substance by one degree. Together with density, it determines volumetric heat capacity.
Laser flash analysis: A method that measures thermal diffusivity from the rear-face temperature response to a short heat pulse. It is a widely used direct measurement technique for solid samples.
Thermal inertia: A material or system's resistance to temperature change, arising from heat storage and heat exchange. Inertia concerns resistance to temperature change, while diffusivity also accounts for conduction.
Thermal effusivity: A material property describing its ability to exchange heat with its surroundings during contact. Effusivity governs contact heat exchange, whereas diffusivity governs internal spreading.
Density: Mass per unit volume of a substance. Density converts mass-specific heat capacity into a volume-based storage measure.

Linked from 22 pages