Radiation Heat Transfer

The Radiation Heat Transfer calculator computes the black-body heat transfer per unit time using the Botzmann constant. 

INSTRUCTIONS:  Choose your preferred units and enter the following:

• (T)  Absolute Temperature
• (A)  Area of Emitting Body

Heat Transfer (q): The calculator returns the heat transfer (q) in Watts.  However this can be automatically converted to other power units via the pull-down menu.

The Math / Science

A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. A white body is one with a "rough surface that reflects all incident rays completely and uniformly in all directions."
A black body in thermal equilibrium (that is, at a constant temperature) emits electromagnetic radiation called black-body radiation. The radiation is emitted according to Planck's law, meaning that it has a spectrum that is determined by the temperature alone (see figure at right), not by the body's shape or composition.

The black-body radiation energy per unit time is proportional to the absolute temperature to the fourth power.  It can be expressed using Stefan-Boltzmann Law as

             q = σ • T⁴ • A

where

• q = heat transfer per unit time (W)
• σ = 5.6703 10^-8 (W/m²K⁴) - The Stefan-Boltzmann Constant
• T = absolute temperature Kelvin (K)
• A  = surface area of the emitting body (m²)

References

• Wikipedia (Black body) : wikipedia.org/wiki/Black_body