
Thermal conductivity is a material property describing the ability to conduct heat. Thermal conductivity can be defined as
"the quantity of heat transmitted through a unit thickness of a material - in a direction normal to a surface of unit area - due to a unit temperature gradient under steady state conditions"
Thermal conductivity units is W/(m K) in the SI system and Btu/(hr ft °F) in the Imperial system.
|
Thermal Conductivity - k - W/(m K) |
|||
|---|---|---|---|
| Material/Substance | Temperature - oC | ||
| 25 | 125 | 225 | |
| Acetals | 0.23 | ||
| Acetone | 0.16 | ||
| Acetylene (gas) | 0.018 | ||
| Acrylic | 0.2 | ||
| Air, atmosphere (gas) | 0.024 | ||
| Air, elevation 10000 m | 0.020 | ||
| Alcohol | 0.17 | ||
| Aluminum | 205 | 215 | 250 |
| Aluminum Brass | 121 | ||
| Aluminum Oxide | 30 | ||
| Ammonia (gas) | 0.022 | ||
| Antimony | 18.5 | ||
| Apple (85.6% moisture) | 0.39 | ||
| Argon (gas) | 0.016 | ||
| Asbestos-cement board | 0.744 | ||
| Asbestos-cement sheets | 0.166 | ||
| Asbestos-cement | 2.07 | ||
| Asbestos, loosely packed | 0.15 | ||
| Asbestos mill board | 0.14 | ||
| Asphalt | 0.75 | ||
| Balsa wood | 0.048 | ||
| Bitumen | 0.17 | ||
| Bitumen/felt layers | 0.5 | ||
| Beef, lean (78.9 % moisture) | 0.43 - 0.48 | ||
| Benzene | 0.16 | ||
| Beryllium | 218 | ||
| Bitumen | 0.17 | ||
| Blast furnace gas (gas) | 0.02 | ||
| Brass | 109 | ||
| Breeze block | 0.10 - 0.20 | ||
| Brick dense | 1.31 | ||
| Brick, insulating | 0.15 | ||
| Brickwork, common (Building Brick) | 0.6 -1.0 | ||
| Brickwork, dense | 1.6 | ||
| Bromine (gas) | 0.004 | ||
| Bronze | 110 | ||
| Butter (15% moisture content) | 0.20 | ||
| Cadmium | 92 | ||
| Calcium silicate | 0.05 | ||
| Carbon | 1.7 | ||
| Carbon dioxide (gas) | 0.0146 | ||
| Carbon monoxide | 0.0232 | ||
| Cellulose, cotton, wood pulp and regenerated | 0.23 | ||
|
Cellulose acetate, molded, sheet |
0.17 - 0.33 | ||
| Cellulose nitrate, celluloid | 0.12 - 0.21 | ||
| Cement, portland | 0.29 | ||
| Cement, mortar | 1.73 | ||
| Chalk | 0. 09 | ||
| Charcoal | 0.2 | ||
| Chlorinated poly-ether | 0.13 | ||
| Chlorine (gas) | 0.0081 | ||
| Chrome Nickel Steel (18% Cr, 8 % Ni) | 16.3 | ||
| Chromium | 94 | ||
| Clay, dry to moist | 0.15 - 1.8 | ||
| Clay, saturated | 0.6 - 2.5 | ||
| Coal | 0.2 | ||
| Cobalt | 69 | ||
| Cod (83% moisture content) | 0.54 | ||
| Concrete, lightweight | 0.1 - 0.3 | ||
| Concrete, medium | 0.4 - 0.7 | ||
| Concrete, dense | 1.0 - 1.8 | ||
| Concrete, stone | 1.7 | ||
| Constantan | 22 | ||
| Copper | 401 | 400 | 398 |
| Corian (ceramic filled) | 1.06 | ||
| Cork board | 0.043 | ||
| Cork, re-granulated | 0.044 | ||
| Cork | 0.07 | ||
| Cotton | 0.04 | ||
| Cotton wool | 0.029 | ||
| Carbon Steel | 54 | 51 | 47 |
| Cotton Wool insulation | 0.029 | ||
| Diamond | 1000 | ||
| Diatomaceous earth (Sil-o-cel) | 0.06 | ||
| Diatomite | 0.12 | ||
| Earth, dry | 1.5 | ||
| Engine Oil | 0.15 | ||
| Ethane (gas) | 0.018 | ||
| Ether | 0.14 | ||
| Ethylene (gas) | 0.017 | ||
| Epoxy | 0.35 | ||
| Ethylene glycol | 0.25 | ||
| Feathers | 0.034 | ||
| Felt insulation | 0.04 | ||
| Fiberglass | 0.04 | ||
| Fiber insulating board | 0.048 | ||
| Fiber hardboard | 0.2 | ||
| Fire-clay brick 500oC | 1.4 | ||
| Fluorine (gas) | 0.0254 | ||
| Foam glass | 0.045 | ||
| Dichlorodifluoromethane R-12 (gas) | 0.007 | ||
| Dichlorodifluoromethane R-12 (liquid) | 0.09 | ||
| Gasoline | 0.15 | ||
| Glass | 1.05 | ||
| Glass, Pearls, dry | 0.18 | ||
| Glass, Pearls, saturated | 0.76 | ||
| Glass, window | 0.96 | ||
| Glass, wool Insulation | 0.04 | ||
| Glycerol | 0.28 | ||
| Gold | 310 | 312 | 310 |
| Granite | 1.7 - 4.0 | ||
| Gravel | 0.7 | ||
| Ground or soil, very moist area | 1.4 | ||
| Ground or soil, moist area | 1.0 | ||
| Ground or soil, dry area | 0.5 | ||
| Ground or soil, very dry area | 0.33 | ||
| Gypsum board | 0.17 | ||
| Hairfelt | 0.05 | ||
| Hardboard high density | 0.15 | ||
| Hardwoods (oak, maple..) | 0.16 | ||
| Helium (gas) | 0.142 | ||
| Honey (12.6% moisture content) | 0.5 | ||
| Hydrochloric acid (gas) | 0.013 | ||
| Hydrogen (gas) | 0.168 | ||
| Hydrogen sulfide (gas) | 0.013 | ||
| Ice (0oC, 32oF) | 2.18 | ||
| Insulation materials | 0.035 - 0.16 | ||
| Iridium | 147 | ||
| Iron | 80 | 68 | 60 |
| Iron, wrought | 59 | ||
| Iron, cast | 55 | ||
| Kapok insulation | 0.034 | ||
| Kerosene | 0.15 | ||
| Krypton (gas) | 0.0088 | ||
| Lead Pb | 35 | ||
| Leather, dry | 0.14 | ||
| Limestone | 1.26 - 1.33 | ||
| Magnesia insulation (85%) | 0.07 | ||
| Magnesite | 4.15 | ||
| Magnesium | 156 | ||
| Marble | 2.08 - 2.94 | ||
| Mercury, liquid | 8.3 | ||
| Methane (gas) | 0.030 | ||
| Methanol | 0.21 | ||
| Mica | 0.71 | ||
| Milk | 0.53 | ||
| Mineral wool insulation materials, wool blankets .. | 0.04 | ||
| Molybdenum | 138 | ||
| Monel | 26 | ||
| Neon (gas) | 0.046 | ||
| Neoprene | 0.05 | ||
| Nickel | 91 | ||
| Nitric oxide (gas) | 0.0238 | ||
| Nitrogen (gas) | 0.024 | ||
| Nitrous oxide (gas) | 0.0151 | ||
| Nylon 6, Nylon 6/6 | 0.25 | ||
| Oil, machine lubricating SAE 50 | 0.15 | ||
| Olive oil | 0.17 | ||
| Oxygen (gas) | 0.024 | ||
| Paper | 0.05 | ||
| Paraffin Wax | 0.25 | ||
| Perlite, atmospheric pressure | 0.031 | ||
| Perlite, vacuum | 0.00137 | ||
| Phenolic cast resins | 0.15 | ||
| Phenol-formaldehyde moulding compounds | 0.13 - 0.25 | ||
| Plaster light | 0.2 | ||
| Plaster, metal lath | 0.47 | ||
| Plaster, sand | 0.71 | ||
| Plaster, wood lath | 0.28 | ||
| Plasticine | 0.65 - 0.8 | ||
| Plastics, foamed (insulation materials) | 0.03 | ||
| Platinum | 70 | 71 | 72 |
| Plutonium | 6.7 | ||
| Plywood | 0.13 | ||
| Polycarbonate | 0.19 | ||
| Polyester | 0.05 | ||
| Polyethylene low density, PEL | 0.33 | ||
| Polyethylene high density, PEH | 0.42 - 0.51 | ||
| Polyisoprene natural rubber | 0.13 | ||
| Polyisoprene hard rubber | 0.16 | ||
| Polymethylmethacrylate | 0.17 - 0.25 | ||
| Polypropylene, PP | 0.1 - 0.22 | ||
| Polystyrene, expanded styrofoam | 0.03 | ||
| Polystyrol | 0.043 | ||
| Polyurethane foam | 0.03 | ||
| Porcelain | 1.5 | ||
| Potato, raw flesh | 0.55 | ||
| Propane (gas) | 0.015 | ||
| Polytetrafluoroethylene (PTFE) | 0.25 | ||
| Polyvinylchloride, PVC | 0.19 | ||
| Pyrex glass | 1.005 | ||
| Quartz mineral | 3 | ||
| Radon (gas) | 0.0033 | ||
| Rock, solid | 2 - 7 | ||
| Rock, porous volcanic (Tuff) | 0.5 - 2.5 | ||
| Rock Wool insulation | 0.045 | ||
| Rubber, cellular | 0.045 | ||
| Rubber, natural | 0.13 | ||
| Salmon (73% moisture content) | 0.50 | ||
| Sand, dry | 0.15 - 0.25 | ||
| Sand, moist | 0.25 - 2 | ||
| Sand, saturated | 2 - 4 | ||
| Sandstone | 1.7 | ||
| Sawdust | 0.08 | ||
| Sheep wool | 0.039 | ||
| Silica aerogel | 0.02 | ||
| Silicone cast resin | 0.15 - 0.32 | ||
| Silicone oil | 0.1 | ||
| Silver | 429 | ||
| Slag wool | 0.042 | ||
| Slate | 2.01 | ||
| Snow (temp < 0oC) | 0.05 - 0.25 | ||
| Sodium | 135 (solid) | 86 (liquid) | |
| Softwoods (fir, pine ..) | 0.12 | ||
| Soil, clay | 1.1 | ||
| Soil, with organic matter | 0.15 - 2 | ||
| Soil, saturated | 0.6 - 4 | ||
|
Steam, saturated |
0.0184 | ||
| Steam, low pressure | 0.0188 | ||
| Steel, Carbon 1% | 43 | ||
| Stainless Steel | 16 | 17 | 19 |
| Straw slab insulation, compressed | 0.09 | ||
| Styrofoam | 0.033 | ||
| Sulfur dioxide (gas) | 0.0086 | ||
| Sugars | 0.087 - 0.22 | ||
| Timber | 0.14 | ||
| Tin Sn | 67 | ||
| Titanium | 22 | ||
| Tungsten | 174 | ||
| Uranium | 27.6 | ||
| Urethane foam | 0.021 | ||
| Vacuum | 0 | ||
| Vermiculite granules | 0.065 | ||
| Vinyl ester | 0.25 | ||
| Water | 0.58 | ||
| Water, vapor (steam) | 0.016 | ||
| Wheat flour | 0.45 | ||
| Wood across the grain, white pine | 0.12 | ||
| Wood across the grain, balsa | 0.055 | ||
| Wood across the grain, yellow pine, timber | 0.147 | ||
| Wood, oak | 0.17 | ||
| Wool, felt | 0.07 | ||
| Wood wool, slab | 0.1 - 0.15 | ||
| Xenon (gas) | 0.0051 | ||
| Zinc Zn | 116 | ||
- 1 W/(m K) = 1 W/(m oC) = 0.85984 kcal/(h m oC) = 0.5779 Btu/(ft h oF) = 0.048 Btu/(in h oF)
- Unit converter - thermal conductivity
- What is conductive heat transfer?
Example - Conductive Heat Transfer through an Aluminum Pot versus a Stainless Steel Pot
The conductive heat transfer through a pot wall can be calculated as
q / A = k dT / s
where
q / A = heat transfer per unit area (W/m2)
k = thermal conductivity (W/mK)
dT = temperature difference (oC)
s = wall thickness (m)
Conductive Heat Transfer through an Aluminum Pot Wall with thickness 2 mm - temperature difference 80oC
Thermal conductivity for aluminum is 215 W/(m K) (from the table above). Conductive heat transfer per unit area can be calculated as
q / A = (215 W/(m K)) (80 oC) / (2 10-3 m)
= 8600000 (W/m2)
= 8600 (kW/m2)
Conductive Heat Transfer through a Stainless Steel Pot Wall with thickness 2 mm - temperature difference 80oC
Thermal conductivity for stainless steel is 17 W/(m K) (from the table above). Conductive heat transfer per unit area can be calculated as
q / A = (17 W/(m K)) (80 oC) / (2 10-3 m)
= 680000 (W/m2)
= 680 (kW/m2)
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