Radiation Constants
Reference data and engineering information about radiation constants for basics applications.
radiationconstants
Overview
Engineering reference data for Radiation Constants in basics.
Key Formulas
Ohm's Law
Voltage = Current × Resistance.
Newton's Second Law
Force = mass × acceleration.
Conservation of Energy
Energy balance.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Voltage | V | |
| Current | A | |
| Resistance | Ω | |
| Force | N | |
| Mass | kg | |
| Acceleration | m/s² |
Radiation Constants Data
The following table provides the radiation constant values and corresponding emissivity coefficients for common building and engineering materials.
21 rows
Product | Radiation Constant(10⁻⁸ W/m²K⁴) | Emissivity (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 - 100 °C | 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 |
Source: engineeringtoolbox.com
Radiation Constant Definition
The radiation constant is a material-specific property used in radiative heat transfer calculations. It is defined as the product of the Stefan-Boltzmann constant (σ) and the emissivity coefficient (ε) of a surface.
The fundamental relationship is:
Where:
- σ is the Stefan-Boltzmann constant.
- ε (epsilon) is the emissivity of the material. It is a dimensionless number between 0 and 1, where *ε = 1 describes a perfect emitter or "black body."