Blackbodies, Emissivity and Real Surfaces

where: ε = emissivity of the radiating surface
Radiation heat transfer from a real surface
Real Surfaces:
The Stefan-Boltzmann Law

Stefan-Boltzmann Law

The maximum radiation rate at which energy can be emitted
from a surface is given by:
= Surface area perpendicular to heat transfer (m2)
= Stefan-Boltzmann Constant = 5.67 x 10-8 W/(m2-K4)
= Absolute temperature of the surface (K)

The emissivity of a surface, ε, quantifies its ability to radiate.

A blackbody has an emissivity of one (ε = 1) and real substances have an emissivity between zero and one (0 <ε< 1).

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Ch 4, Lesson B, Page 22 - Blackbodies, Emissivity and Real Surfaces