熱擴散率

在傳熱分析中，熱擴散率（符號：${\displaystyle \alpha \,}$，但注意${\displaystyle \kappa }$、${\displaystyle D}$和${\displaystyle k}$都很常用）是熱導率與容積熱容之比。

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

其中：

• ${\displaystyle k\,}$：熱導率（單位：W/(m K)）
• ${\displaystyle \rho c_{p}\,}$：容積熱容（單位：J/(m³K)）
• ${\displaystyle \rho \,}$：密度（單位：kg/(m³)）
• ${\displaystyle c_{p}\,}$：比熱容（單位：J/(kg K)）

熱擴散率的單位是m²/s。

對於普通的岩石來說，${\displaystyle \alpha \,}$ ~ 10^-6 m²/s。在300K，空氣的熱擴散率是0.000024 m²/s。

對於空氣的熱擴散率與絕對溫度之間的關係，參見[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 (mm2/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]
鋼, AISI 1010 (0.1% carbon)	18.8	[8]
氧化鋁 (polycrystalline)	12.0
鋼, 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]

參見

• 熱擴散
• 熱容
• 比熱容
• 熱傳導方程式
• 熱導率

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14. ^ 引用錯誤：沒有為名為AJP的參考文獻提供內容