4 Radiation

Another mechanism of heat transfer in addition to conduction and convection is radiative heat transfer, which involves the transport of thermal energy by electromagnetic waves. Since the application of thermal radiation to electronic equipment generally occurs in a relatively simple form, this chapter will be limited to basic knowledge of thermal radiation.

Gases that do not absorb thermal radiation are known as nonparticipating gases. Generally no significant absorption takes place when thermal radiation passes through air. Participating media, or fluids that will absorb some thermal radiation, include carbon monoxide, water vapor, and liquids.