热扩散率

在传热分析中，热扩散率（符号：${\displaystyle \alpha \,}$，但注意${\displaystyle \kappa }$、${\displaystyle D}$和${\displaystyle k}$都很常用）是热导率与容积热容之比。

${\displaystyle \alpha ={k \over {\rho c_{p}}}}$

其中：

• ${\displaystyle k\,}$：热导率（单位：W/(m K)）
• ${\displaystyle \rho c_{p}\,}$：容积热容（单位：J/(m^3K)）
• ${\displaystyle \rho \,}$：密度（单位：kg/(m^3)）
• ${\displaystyle c_{p}\,}$：比热容（单位：J/(kg K)）

热扩散率的单位是m^2/s。

对于普通的岩石来说，${\displaystyle \alpha \,}$ ~ 10^-6 m^2/s。在300K，空气的热扩散率是0.000024 m^2/s。

对于空气的热扩散率与绝对温度之间的关系，参见[1]。

部分材料與物質的熱擴散率

部分材料與物質的熱擴散率[1]

材質	熱擴散率 (mm^2/s)	來源
Pyrolytic graphite, parallel to layers	1220
碳/碳纖維 at 25 °C	216.5	[2]
氦氣 (300 K, 1 atm)	190	[3]
純銀 (99.9%)	165.63
氫氣 (300 K, 1 atm)	160	[3]
金	127	[4]
銅 at 25 °C	111	[2]
鋁	97	[4]
矽	88	[4]
鋁-10矽-錳-鎂 (Silafont 36) at 20 °C	74.2	[5]
6061-T6 鋁合金	64	[4]
鉬 (99.95%) at 25 °C	54.3	[6]
鋁-5鎂-2矽-錳 (Magsimal-59) at 20 °C	44.0	[7]
錫	40	[4]
水蒸氣 (1 atm, 400 K)	23.38
鐵	23	[4]
氬氣 (300 K, 1 atm)	22	[3]
氮氣 (300 K, 1 atm)	22	[3]
空氣 (300 K)	19	[4]
钢, AISI 1010 (0.1% carbon)	18.8	[8]
氧化鋁 (polycrystalline)	12.0
钢, 1% carbon	11.72
Si3N4 with CNTs 26 °C	9.142	[9]
Si3N4 without CNTs 26 °C	8.605	[9]
304不鏽鋼 at 27 °C	4.2	[4]
熱解石墨, normal to layers	3.6
310不鏽鋼 at 25 °C	3.352	[10]
Inconel 600 at 25 °C	3.428	[11]
石英	1.4	[4]
砂岩	1.15
冰 at 0 °C	1.02
二氧化矽 (polycrystalline)	0.83	[4]
磚塊, common	0.52
玻璃窗戶	0.34
磚塊, adobe	0.27
PC塑膠 (polycarbonate) at 25 °C	0.144	[12]
水 at 25 °C	0.143	[12]
PTFE塑膠 (Polytetrafluorethylene) at 25 °C	0.124	[13]
PP塑膠 (polypropylene) at 25 °C	0.096	[12]
尼龍	0.09
橡膠	0.089 - 0.13	[14]
木材 (黃松)	0.082
石蠟 at 25 °C	0.081	[12]
PVC塑膠 (polyvinyl chloride)	0.08	[4]
引擎用油 (saturated liquid, 100 °C)	0.0738
酒精	0.07	[4]

參考資料

1. Brown; Marco. Introduction to Heat Transfer 3rd. McGraw-Hill. 1958.  and Eckert; Drake. Heat and Mass Transfer. McGraw-Hill. 1959. ISBN 978-0-89116-553-8.  cited in Holman, J.P. Heat Transfer 9th. McGraw-Hill. 2002. ISBN 978-0-07-029639-8. 
2. V. Casalegno; P. Vavassori; M. Valle; M. Ferraris; M. Salvo; G. Pintsuk. Measurement of thermal properties of a ceramic/metal joint by laser flash method. Journal of Nuclear Materials. 2010, 407 (2): 83. Bibcode:2010JNuM..407...83C. doi:10.1016/j.jnucmat.2010.09.032. 
3. Lide, David R. (编). CDC Handbook of Chemistry and Physics 71st. Boston: Chemical Rubber Publishing Company. 1992.  cited in Baierlein, Ralph. Thermal Physics. Cambridge, UK: Cambridge University Press. 1999: 372 [1 December 2011]. ISBN 978-0-521-59082-2.  含有內容需登入查看的頁面 (link)
4. Jim Wilson. Materials Data. August 2007 [2021-11-07]. （原始内容存档于2021-11-08）. 
5. P. Hofer; E. Kaschnitz. Thermal diffusivity of the aluminium alloy Al-10Si-Mn-Mg (Silafont 36) in the solid and liquid states. High Temperatures – High Pressures. 2011, 40 (3–4): 311 [2021-11-07]. （原始内容存档于2016-03-04）. 
6. A. Lindemann; J. Blumm. Measurement of the Thermophysical Properties of Pure Molybdenum. 17th Plansee Seminar 3. 2009. 
7. E. Kaschnitz; M. Küblböck. Thermal diffusivity of the aluminium alloy Al-5Mg-2Si-Mn (Magsimal-59) in the solid and liquid states. High Temperatures – High Pressures. 2008, 37 (3): 221 [2021-11-07]. （原始内容存档于2016-03-04）. 
8. Lienhard, John H. Lienhard, John H. A Heat Transfer Textbook 5th. Dover Pub. 2019: 715. 
9. O. Koszor; A. Lindemann; F. Davin; C. Balázsi. Observation of thermophysical and tribological properties of CNT reinforced Si₃ N₄. Key Engineering Materials. 2009, 409: 354. S2CID 136957396. doi:10.4028/www.scientific.net/KEM.409.354. 
10. J. Blumm; A. Lindemann; B. Niedrig; R. Campbell. Measurement of Selected Thermophysical Properties of the NPL Certified Reference Material Stainless Steel 310. International Journal of Thermophysics. 2007, 28 (2): 674. Bibcode:2007IJT....28..674B. S2CID 120628607. doi:10.1007/s10765-007-0177-z. 
11. J. Blumm; A. Lindemann; B. Niedrig. Measurement of the thermophysical properties of an NPL thermal conductivity standard Inconel 600. High Temperatures – High Pressures. 2003–2007, 35/36 (6): 621 [2021-11-07]. doi:10.1068/htjr145. （原始内容存档于2015-09-24）. 
12. J. Blumm; A. Lindemann. Characterization of the thermophysical properties of molten polymers and liquids using the flash technique. High Temperatures – High Pressures. 2003–2007, 35/36 (6): 627. doi:10.1068/htjr144. 
13. J. Blumm; A. Lindemann; M. Meyer; C. Strasser. Characterization of PTFE Using Advanced Thermal Analysis Technique. International Journal of Thermophysics. 2011, 40 (3–4): 311. Bibcode:2010IJT....31.1919B. S2CID 122020437. doi:10.1007/s10765-008-0512-z. 
14. 引用错误：没有为名为AJP的参考文献提供内容

参见

• 热扩散
• 热容
• 比热容
• 热传导方程式
• 热导率