Stefan–Boltzmann Radiation

Net radiative heat transfer between two grey surfaces: Q = ε·σ·A·(T₁⁴ − T₂⁴).

Heat transferRadiation

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Formula, assumptions, and limits

Q = \varepsilon \cdot \sigma \cdot A \cdot (T_1^4 - T_2^4), \; \sigma = 5.67 \times 10^{-8}

Symbol	Meaning	Unit
$ε$	Emissivity
$σ$	Stefan-Boltzmann constant	W/(m²·K⁴)
$A$	Surface area	m²
$T_1, T_2$	Hot and cold surface temperatures	K
$Q$	Radiative heat flow	kW

Source: Incropera - Fundamentals of Heat and Mass Transfer

Net radiative heat transfer between two grey surfaces: Q = \u03b5\u00b7\u03c3\u00b7A\u00b7(T\u2081\u2074 \u2212 T\u2082\u2074).