Radiative Heat Transfer

Radiation

Radiative heat transfer is the transport of thermal energy emitted as electromagnetic waves. It is attributed to changes in electron configuration within the atoms of the target matter. No medium (i.e. physical contact or fluid motion) is required for this mode of heat transfer, as it is spontaneously emitted.

The maximum flux at which radiation may be emitted by a body is governed by the Stefan-Boltzmann Law:

$$ q^{''} = \frac{q}{A} = \sigma T^4 $$

where

$ q^{''} [\frac{W}{m^2}] $ = rate of heat flow per unit area
$ q [W] $ = rate of heat emission
$ A [m^2] $ = area of radiating surface
$ \sigma = 5.67*10^{-8} [\frac{W}{m^2 K^4}] $ = Stefan-Boltzmann constant
$ T [K] $ = temperature of the radiating surface

When also considering the the energy received by the body from its surroundings, the net exchange of radiation can be calculated as:

$$ q^{''}_{system-surroundings} = \sigma (T_{system}^{4}-T_{surroundings}^{4}) $$