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Encyclopedia > Thermal diffusivity

In heat transfer analysis, thermal diffusivity (symbol: α) is the ratio of thermal conductivity to heat capacity.

where


k is thermal conductivity, measured in watts per metre-kelvin


ρcp is the volumetric heat capacity, measured in joules per cubic metre-kelvin


The SI units are square metres per second or mē/s.


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'.


  Results from FactBites:
 
Method and apparatus for measuring thermal diffusivity by ac joule-heating - Patent 5080495 (5943 words)
The method for measuring thermal diffusivity according to the non-steady state method is characterized in that the thermal diffusivity is determined by producing forcibly a thermally non-equilibrium state in a sample and measuring the temperature variation of the sample caused by the subsequent relaxation of the state.
The heat energy is transmitted by thermal conduction, causing a periodic temperature oscillation in the gas in the sealed cell in contact with the opposite measurement surface and producing a periodic sound wave in agreement in phase with the temperature oscillation on the measurement surface of the sample.
The thermal conductivity thus obtained has a peak in the vicinity of the glass transition temperature as in the case of the thermal diffusivity, and its whole behavior is also similar to that of the thermal diffusivity.
  More results at FactBites »


 

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