Radiation Heat Transfer⚠ unverified
Physics / Heat Transfer · Net radiative heat transfer between two surfaces (Stefan-Boltzmann)
Parameters
| Input | Symbol | Unit | Default | Description |
|---|---|---|---|---|
| epsilon | ε | — | 0.9 | Emissivity |
| A | A | m^2 | 1.0 | Surface area |
| T1 | T1 | K | 400.0 | Hot surface temperature |
| T2 | T2 | K | 300.0 | Cold surface temperature |
| Output | Symbol | Unit | Description |
|---|---|---|---|
| Q | Q | W | Net heat rate |
The science & history
Understanding the Parameters
-
$\varepsilon$ — 1 for blackbody; real surfaces lower. View factors and multi-surface enclosures need more terms than this formula.
-
$T^4$ — radiation is extremely sensitive to temperature; use kelvin only.
- $\sigma$ — Stefan–Boltzmann constant (built into the formula, not an input).
Derivation (Approaching a Proof)
Blackbody emissive power $E_b = \sigma T^4$ (Stefan–Boltzmann). A gray body emits $\varepsilon\sigma T^4$. Net exchange with large black surroundings at $T_2$ is $Q = \varepsilon\sigma A(T_1^4 - T_2^4)$. More general enclosures use radiosity networks.
History
Stefan (1879) and Boltzmann (1884) established the $T^4$ law; it underpins furnace, spacecraft, and electronics thermal design.
Related Concepts: Convection Heat Transfer, 1D Steady Conduction, Heat Flux
Notes: Registry calculator radiation-heat-transfer (unverified). Simple two-temperature form;
$\sigma$ implicit.