Know More About Thermal Conductivity

pcb thermal new floor
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 500^oC	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 (0^oC, 32^oF)	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 < 0^oC)	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 80^oC

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 80^oC

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^-3m)

= 680000 (W/m²)

= 680 (kW/m²)

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