In
heat transfer analysis, thermal diffusivity is the
thermal conductivity divided by
density and
specific heat capacity at constant pressure.[1] It is a measure of the rate of heat transfer inside a material. It has units of m2/s. Thermal diffusivity is usually denoted by lowercase
alpha (α), but a, h, κ (
kappa),[2]K,[3] and D are also used.
one way to view thermal diffusivity is as the ratio of the
time derivative of
temperature to its
curvature, quantifying the rate at which temperature concavity is "smoothed out". Thermal diffusivity is a contrasting measure to
thermal effusivity.[6][7] In a substance with high thermal diffusivity, heat moves rapidly through it because the substance conducts heat quickly relative to its volumetric heat capacity or 'thermal bulk'.
Thermal diffusivity is often measured with the
flash method.[8][9] It involves heating a strip or cylindrical sample with a short energy pulse at one end and analyzing the temperature change (reduction in amplitude and phase shift of the pulse) a short distance away.[10][11]
Thermal diffusivity of selected materials and substances
Thermal diffusivity of selected materials and substances[12]
^Hetnarski, Richard B.; Eslami, M. Reza (2009). Thermal Stresses - Advanced Theory and Applications (Online-Ausg. ed.). Dordrecht: Springer Netherlands. p. 170.
doi:
10.1007/978-3-030-10436-8.
ISBN978-1-4020-9247-3.
^
J. Blumm; J. Opfermann (2002). "Improvement of the mathematical modeling of flash measurements". High Temperatures – High Pressures. 34 (5): 515.
doi:
10.1068/htjr061.
^Brown; Marco (1958). Introduction to Heat Transfer (3rd ed.). McGraw-Hill. and Eckert; Drake (1959). Heat and Mass Transfer. McGraw-Hill.
ISBN978-0-89116-553-8. cited in Holman, J.P. (2002). Heat Transfer (9th ed.). McGraw-Hill.
ISBN978-0-07-029639-8.
^
abV. Casalegno; P. Vavassori; M. Valle; M. Ferraris; M. Salvo; G. Pintsuk (2010). "Measurement of thermal properties of a ceramic/metal joint by laser flash method". Journal of Nuclear Materials. 407 (2): 83.
Bibcode:
2010JNuM..407...83C.
doi:
10.1016/j.jnucmat.2010.09.032.
^
abcdLide, David R., ed. (1992). CDC Handbook of Chemistry and Physics (71st ed.). Boston: Chemical Rubber Publishing Company. cited in Baierlein, Ralph (1999). Thermal Physics. Cambridge, UK: Cambridge University Press. p.
372.
ISBN978-0-521-59082-2. Retrieved 1 December 2011.
^Lienhard, John H. Lienhard, John H. (2019). A Heat Transfer Textbook (5th ed.). Dover Pub. p. 715.{{
cite book}}: CS1 maint: multiple names: authors list (
link)
^
abO. Koszor; A. Lindemann; F. Davin; C. Balázsi (2009). "Observation of thermophysical and tribological properties of CNT reinforced Si3 N4". Key Engineering Materials. 409: 354.
doi:
10.4028/www.scientific.net/KEM.409.354.
S2CID136957396.