Commonly used thermal conductivity values

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Common thermal conductivity values: I. Thermal conductivity of solids. The common thermal conductivity values for solids are shown in Table 4-1. Of all solids, metals are the best conductors of heat. The thermal conductivity of pure metals generally decreases as the temperature rises. The purity of the metal has a significant impact on the thermal conductivity; for example, the thermal conductivity of ordinary carbon steel with 1% carbon content is 45 W/m·K, while that of stainless steel is only 16 W/m·K. Table 4-1 Thermal conductivity of common solid materials
Solid | Temperature, °C | Thermal conductivity, λ, W/m·K
Aluminum | 300 | 230
Cadmium | 18 | 94
Copper | 100 | 377
Pig iron | 18 | 61
Cast iron | 53 | 48
Lead | 100 | 33
Nickel | 100 | 57
Silver | 100 | 412
Steel (1%C) | 18 | 45
Metals used in ships | 30 | 113
Brass | 189 |
Stainless steel | 20 | 16
Graphite | 0 | 151
Asbestos board | 50 | 0.17
Asbestos | 0–100 | 0.15
Concrete | 0–100 | 1.28
Firebrick | 1.04 | ①
Insulation brick | 0–100 | 0.12–0.21
Building brick | 20 | 0.69
Fleece | 0–100 | 0.047
Cotton | 30 | 0.050
Glass | 30 | 1.09
Mica | 50 | 0.43
Rigid rubber | 0 | 0.15
Sawdust | 20 | 0.052
Cork | 30 | 0.043
Glass wool | – | 0.041
85% magnesium oxide | – | 0.070

II. Thermal conductivity of liquids
Liquids are divided into metallic liquids and non-metallic liquids; the former have higher thermal conductivity, while the latter have lower values. Among non-metallic liquids, water has the highest thermal conductivity; aside from water and glycerin, the thermal conductivity of the vast majority of liquids decreases slightly as the temperature rises. Generally, the thermal conductivity of a solution is lower than that of a pure liquid. Table 4-2 and Figure 4-6 list the thermal conductivity values of several liquids. Table 4-2 Thermal conductivity of liquids Liquid Temperature, °C Thermal conductivity, λ W/m·K 50% acetic acid 20 0.35 Propanone 30 0.17 Aniline 0–20 0.17 Benzene 30 0.16 30% calcium chloride solution 30 0.55 80% ethanol 20 0.24 60% glycerin 20 0.38 40% glycerin 20 0.45 Heptane 30 0.14 Mercury 28 8.36 90% sulfuric acid 30 0.36 60% sulfuric acid 30 0.43 Water 30 0.62 III. Thermal conductivity of gases The thermal conductivity of gases increases as the temperature rises. Within the normal pressure range, its thermal conductivity changes very little with pressure; it is only when the pressure exceeds 196200 kN/m2 or is less than 2.67 kN/m2 (20 mmHg) that the thermal conductivity increases as pressure rises. Therefore, in engineering calculations, the effect of pressure on the thermal conductivity of gases can often be ignored. Gases have a very low thermal conductivity, which is unfavorable for heat conduction but advantageous for insulation. The thermal conductivity values of several common gases are shown in Table 4-3. Table 4-3 Thermal conductivity of gases Gas Temperature, °C Thermal conductivity, λ, W/m·K Hydrogen 0 0.17 Carbon dioxide 0 0.015 Air 0 0.024 Air 100 0.031 Methane 0 0.029 Water vapor 100 0.025 Nitrogen 0 0.024 Ethylene 0 0.017 Oxygen 0 0.024 Ethane 0 0.018