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열유체, 에너지 실험
KAIST 기계공학과
정 상 권
• 흥미로운 열유체 현상
이번 시간에는!
흥미로운 열유체 현상
KAIST 기계공학과
정 상 권
복빙 현상 (Regelation of ice) 유체 현상 열영동 현상 (thermophoresis)
[ 학 습 목 차 ]
Why do skis slide and snowballs stick?
Regelation of ice ?
복빙 현상 (Regelation of ice)
Temperature
Gas
Critical
point Liquid
Triple
point
Solid
L
V
V
S
S
Pre
ssu
re
Pressure = Mg/wire contact area
Melting curve
Liquid
Solid
Temperature (K)
Pre
ssure
(M
Pa)
250 255 260 265 270 275
0
50
100
150
200
250
복빙 현상 (Regelation of ice)
복빙 현상 (Regelation of ice)
• Viscosity is a measure of the resistance to flow; internal friction in a fluid.
#1
Viscosity
Viscosity
• Viscous fluid always tends to cling to a solid surface in contact with it.
No slip condition !
#2 #3
ReUL UL
Re >> 1 : inertia effect is dominant.
Re << 1 : viscous effect is dominant.
Reynolds number
• Reynolds number: Primary parameter characterizing the viscous behavior of a
fluid.
#4 #5
ReUL UL
• Reynolds number:
Primary parameter characterizing
the viscous behavior of a fluid.
Re >> 1 : inertia effect is dominant.
Re << 1 : viscous effect is dominant.
Reynolds number
Re = 0.1
Impulsive rotation of a tank
Re = 100
Liquid jet
Re = 0.05 10 200 3000
Reynolds number
#6 #7 #8
Re = 50
• Flow past a cylinder
Re = 1000
Reynolds number
#9 #10
Thermophoresis
• Movement in temperature gradient
Thigh
Tlow
Thermophoresis
Pentane (C5H12) transfer
by evaporation (liquid vapor) and condensation (vapor liquid)
Normal boiling point
~ 36 ˚C
Thermophoresis
자료 출처 #1 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
#2 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
#3 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
#4 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
#5 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
#6 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
#7 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
#8 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
#9 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
#10 Homsy et al., Multimedia Fluid Mechanics, 2nd ed., Cambridge University Press
흥미로운 열유체 현상
KAIST 기계공학과
정 상 권
[ 학 습 목 차 ]
고체+액체+기체가 공존하는 상태 (Triple line) 열음향 에너지 (thermoacoustic energy) 변환 스털링 엔진 (Stirling engine)
고체+액체+기체가 공존하는 상태 (Triple line)
Solid Nitrogen by Evaporation Cooling
Boiling
Vacuum Pumping
Evaporation Cooling
Solid Nitrogen
Liquid Nitrogen
Critical
point
Triple
point
Solid Liquid
Gas
T (K)
P (kPa)
63.2 77.4
101.3
12.8
•고체+액체+기체가 공존하는 상태 (Triple line)
동영상
•열음향 에너지
(thermoacoustic energy) 변환
#1
•열음향 에너지 (thermoacoustic energy) 변환
동영상
•스털링 엔진 (Stirling engine)
•스털링 엔진
(Stirling engine)
삽화 제작하여 개발(저작권 미결)
촬영은 동영상으
로 나오나 현재 스틸 삽화로 대체하여 개발
(뒤에 관련 동영상이 나오니 괜찮음)
•스털링 엔진 (Stirling engine)
동영상
자료 출처 #1 çengel, Y.A. and Boles, M.A. Thermodynamics – An Engineering Approach, 5th Edition, McGraw-Hill, 2006, p.282
흥미로운 열유체 현상
KAIST 기계공학과
정 상 권
[ 학 습 목 차 ]
액체/기체의 구분이 없는 상태 (Critical point)
Thermofluids
#1
Introduction to Critical Point • Critical point : end point of phase equilibrium curve.
No phase change above critical point.
#2
Non-flammable, safe !
• PRESSURE
Thermofluids
#3 #4
• Isotherms of carbon dioxide in the neighborhood of the critical point
동영상
•액체/기체의 구분이 없는 상태 (Critical point)
critical opalescence
자료 출처 #1 çengel, Y.A. and Boles, M.A. Thermodynamics – An Engineering Approach, 5th Edition, McGraw-Hill, 2006, p.119
#2 Interactive 3D phase diagrams using Jmol. A. Herráez, R.M. Hanson and L. Glasser (2009) J. Chem. Educ. 86: 566
#3 çengel, Y.A. and Boles, M.A. Thermodynamics – An Engineering Approach, 5th Edition, McGraw-Hill, 2006, p.23
#4 çengel, Y.A. and Boles, M.A. Thermodynamics – An Engineering Approach, 5th Edition, McGraw-Hill, 2006, p.25
