KEVOS® MAKEOS · Materials
Radiant Heat Loss
How much heat does this hot surface radiate to its surroundings?
Net radiant heat exchange between a surface and large surroundings from area, emissivity and temperatures (Stefan–Boltzmann law), with the equivalent radiation coefficient.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Surface area | m² | Radiating surface area. |
| Emissivity | Emissivity of the surface (oxidised steel about 0.8, painted 0.9, polished aluminium about 0.05). | |
| Surface temperature | °C | Surface temperature. |
| Surroundings temperature | °C | Temperature of the surrounding walls or space (large surroundings). |
Method and formulas
- Q = ε σ A (Ts⁴ − Ta⁴), with σ = 5.670 × 10⁻⁸ W/m²K⁴ and temperatures in kelvin.
- Equivalent coefficient h_r = Q ÷ (A (Ts − Ta)).
- Example: 2 m² at 300 °C with ε 0.8 radiates about 9.0736 kW.
Limitations
- Grey surface facing large surroundings; view factors for nearby surfaces are not included.
- Convection adds to the total loss.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Estimate heat loss from furnace walls, ovens and hot parts
- Compare surface finishes (emissivity)
- Add radiation to convection estimates
Who it is for
- Process engineers
- Energy managers
- Maintenance engineers
What you get
- Net radiant heat
- Heat flux
- Equivalent radiation coefficient
Interpreting the result
- Low-emissivity cladding greatly reduces radiant losses from hot equipment.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 371–378. Topic reference; no source tables or recommended settings are reproduced.
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