Building Materials - Radiation Constants
The radiation constant is the product between the Stefan-Boltzmann constant and the emissivity constant for a material.
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The radiation constant is the product between the Stefan-Boltzmann constant - σ - and the emissivity constant - ε - of a material.
The radiation constant for some typical products:
| Product | Radiation Constant (10-8 W/m2 K4) | Emissivity Constant - ε - |
|---|---|---|
| Black body | 5.7 | 1 |
| Brass, dull | 1.3 | 0.22 |
| Brick, red | 5.3 | 0.93 |
| Cast iron, rough oxidized | 5.1 | 0.9 |
| Copper, polished | 0.28 | 0.04 |
| Cotton | 4.4 | 0.77 |
| Glass | 5.1 | 0.9 |
| Lampblack paint | 5.5 | 0.96 |
| Oil paint | 5.4 | 0.94 |
| Paper | 3.1 | 0.55 |
| Plaster | 5.6 | 0.98 |
| Sand | 5.1 | 0.9 |
| Silk | 4.3 | 0.75 |
| Silver, polished | 0.17 | 0.03 |
| Tin, unoxidized | 0.23 | 0.04 |
| Water, 0 - 100oC | 5.4 | 0.95 |
| Wood | 5.1 | 0.9 |
| Wool | 4.3 | 0.75 |
| Wrought iron, dull oxidized | 5.4 | 0.9 |
| Wrought iron, polished | 1.6 | 0.25 |
| Zinc, tarnished | 1.4 | 0.25 |
σ = 5.6703 10-8 (W/m2K4) = 0.1714 10-8 (Btu/(h ft2 oR4) ) - Stefan-Boltzmann Constant
ε = emissivity coefficient of the object (ε = 1 for a black body)
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