60
Chapter 2
Introduction to Conduction
2.2
The Thermal Properties of Matter
2.2.1
Thermal Conductivity
The Solid State
2.2
Foams
Carbon
dioxide
0.01
61
The Thermal Properties of Matter
Zinc
Silver
PURE METALS
Nickel
Aluminum
ALLOYS
Plastics
Ice
Oxides
NONMETALLIC SOLIDS
Fibers
Oils Water
LIQUIDS
Hydrogen
GASES
0.1
Mercury
1
10
Thermal conductivity (W/m•K)
100
1000
FIGURE 2.4 Range of thermal conductivity for various states of matter at normal
temperatures and pressure.
Chapter 2
Introduction to Conduction
500
400
Silver
Copper
300
Gold
Aluminum
Aluminum
alloy 2024
Tungsten
200
100
Thermal conductivity (W/m•K)
62
Platinum
50
Iron
20
Stainless steel,
AISI 304
10
Aluminum oxide
5
Pyroceram
2
1
100
Fused quartz
300
500
1000
Temperature (K)
2000
4000
FIGURE 2.5 The temperature dependence of the thermal conductivity of selected solids.
The Solid State: Micro- and Nanoscale Effects
2.2
63
The Thermal Properties of Matter
1
2
( )
1
( )
FIGURE 2.6 Electron or phonon trajectories in (a) a relatively thick film and (b) a relatively
thin film with boundary effects.
TABLE 2.1 Mean free path and critical film thickness for
various materials at T 300 K [3,4]
Chapter 2
Introduction to Conduction
FIGURE 2.7 Measured
thermal conductivity of yttriastabilized zirconia as a function
of temperature and mean grain
size [3].
2.5
= 98 nm
2
Thermal conductivity (W/m•K)
64
= 55 nm
= 32 nm
1.5
= 23 nm
1
= 10 nm
0.5
mfp
0
0
100
( = 300 K) = 25 nm
200
300
Temperature (K)
The Fluid State
400
500
2.2
65
The Thermal Properties of Matter
0.3
Hydrogen
= 2.018
Thermal conductivity (W/m•K)
Helium 4.003
0.2
Water
(steam, 1 atm)
18.02
0.1
Carbon dioxide
44.01
Air
28.97
0
0
Freon 12
120.9
200
400
600
Temperature (K)
800
1000
FIGURE 2.8 The temperature dependence of the thermal conductivity of selected gases at
normal pressures. Molecular weights ( ) of the gases are also shown.
The Fluid State: Micro- and Nanoscale Effects
Chapter 2
Introduction to Conduction
0.8
Water
0.6
Thermal conductivity (W/m•K)
66
Ammonia
0.4
Glycerine
0.2
Freon 12
0
200
300
400
Temperature (K)
Engine
oil
500
FIGURE 2.9 The temperature dependence of the thermal conductivity of selected
nonmetallic liquids under saturated conditions.
Insulation Systems
2.2
67
The Thermal Properties of Matter
Effective thermal conductivity (W/m•K)
0.014
0.012
0.01
0.008
0.006
0.004
0.002
0
10
3
10
2
10
1
100
Pressure (atm)
FIGURE 2.10 Measured thermal conductivity of carbon-doped silica aerogel as a function of
pressure at T 300 K [10].
2.2.2
Other Relevant Properties
v
68
Chapter 2
Introduction to Conduction
EXAMPLE 2.1
SOLUTION
Known:
Find:
Properties:
2.2
The Thermal Properties of Matter
Comments:
5
69