7 熱物理
Why are black robes worn in extreme ly hot climates?
黑袍下的秘密
熱物理 (Thermal Physics)
1.
溫度與熱2.
熱膨脹3.
相變化( phase changes )4.
熱傳遞( Heat transfer )5.
氣體動力論( Kinetic Theory of gas es )6.
引擎與致冷機7.
傳統能源與再生能源7.1 溫度與熱
•
The Celsius and Fahrenheit temper ature scales• TF = (9/5)TC+32°
• Kelvin Scale
• TC = T – 273.15°
• T3 = 273.16K triple point
水的三相點溫度 triple point
水的三相點溫度
凱氏攝氏與華氏溫標
攝氏與華氏溫標
從最高溫到最低溫
溫度計
•
定容氣體溫度計•
熱偶溫度計•
Bimetallic strip•
Optical pyrometer定容氣體溫度計
) )(
16 . 273 (
) (
3 3
3 3 3
0
p K p
p T p
T
Cp T
gh p
p
Cp T
凱氏溫標的定義
熱偶溫度計 (thermocoupl e)
-240
°
C– 2700°
C-240
°
C– 2700°
CBimetallic strip and
Optical pyrometer
熱( heat )的定義和單位
• J = Joule (焦耳)
• Cal = calorie (卡洛里)
• Btu = British Thermal Unit
Heat is the energy that is transferred between a system and its environment because of a temperature difference that exists between them
例一 A candy bar 350 大卡
•
供 100W 燈泡使用 4.1h•
慢跑 3 ~ 4mi7.2 熱膨脹
Bimetallic strip switch
線膨脹與體膨脹
3
T V
V
T L
L
例二 熱應力 (Thermal stress)
2 7
1 6
2 11
0 0 0
/ 10
6 . 4
) 19
)(
10 12
)(
/ 10
0 . 2 (
m N
C C
m N
T L Y
T Y L
L Y L
t
例三 Delivering diesel oil from Las Vegas to Payson
• 9785 gal, temperature difference 41°
F
• = 9.510-4/C ° - diesel fuel
• = 11 10-6/C ° - steel tank
gal 212
) F 41 )(
C / 10
5 . 9 )(
9785
(
4