THERMAL DIFFUSIVITY

In heat transfer analysis, 'thermal diffusivity' (symbol: ) is the ratio of thermal conductivity to volumetric heat capacity.
:
ho c_p}}
where:

★ 'k' is thermal conductivity (SI units: watts per metre-kelvin, W∙m^-1∙K^-1)

★ 'ρc_p' is the volumetric heat capacity (density times specific heat capacity; SI units: joules per cubic metre-kelvin, J∙m^-3∙K^-1)
The SI units for thermal diffusivity are square metres per second or m²∙s^-1.
Substances with high thermal diffusivity rapidly adjust their temperature to that of their surroundings, because they conduct heat quickly in comparison to their thermal 'bulk'. For common rock material, α ~ 10^-6 m²∙s^-1.
For a plot of thermal diffusivity of air as a function of absolute temperature see James Ierardi's Fire Protection Engineering Site

Contents

See also

See also

★ Heat capacity

★ Specific heat capacity

★ Heat equation

★ Thermal conductivity

★ Thermal effusivity

★ Thermal time constant