Radiative Heat Transfer
Definition
Transfer of heat by electromagnetic waves (infrared). Scales as the fourth power of absolute temperature; at near-flashover temperatures it can simultaneously ignite all exposed fuel surfaces.
- Mechanism
- Electromagnetic (infrared) energy transfer
- Scaling
- Proportional to absolute temperature to the 4th power
- Fire relevance
- Drives flashover ignition of exposed fuels
Common questions
How does radiative heat transfer differ from conduction and convection in a fire?+
Conduction and convection require direct contact or a moving fluid medium, while radiation transfers energy through electromagnetic waves across open space, which is why a hot ceiling layer can pre-heat and ignite fuel packages it never physically touches.
Why is the fourth-power temperature scaling significant for reconstructing flashover?+
Because radiative output rises so steeply with temperature, a relatively modest increase in upper-layer gas temperature can produce a large jump in radiant heat flux to the floor, which helps explain why flashover can appear to occur suddenly.
Related terms
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- Conductive Heat Transfer
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- Convective Heat Transfer
- Transfer of heat by bulk movement of a fluid (gas or liquid). In compartment fires, the buoyant hot gas plume carries most...
- Fire Tetrahedron
- The model of sustained combustion requiring four concurrent elements: fuel, oxidiser, heat, and an uninhibited radical chain reaction. Replacing the older fire...
- Flaming Combustion
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- Flash Point
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- Glowing (Smouldering) Combustion
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