The transfer of heat energy by radiation can occur in a vacuum, unlike conduction and convection. Heat radiation is the same form of wave energy transfer as light, radio, and x-ray wave energy. The rate of emmission of heat energy is related to the temperature difference, the distance between the surfaces, and the emissivity of the surface. Bright reflective surfaces have the lowest emissivity values.

Radiation is heat transfer by the emission of electromagnetic waves which carry energy away from the emitting object. For ordinary temperature (less than red hot), the radiation is in the infrared region of the electromagnetic spectrum. The relationship governing radiation from hot objects is called the Stefan-Boltzmann law.




Related References:

Types of heat exchangers
Shell and tube heat exchanger
Plate Heat Exchanger - Efficiency and Flexibility
U Tube heat exchanger
Regenerative heat exchanger
Adiabatic wheel heat exchanger
Plate fin heat exchanger
Fluid heat exchangers
Phase-change heat exchanger
Parallel Flow Heat Exchanger
Counter Flow Heat Exchanger
Cross Flow Heat Exchanger
Spiral heat exchangers
Shell and Coil Heat Exchangers
Brazed Heat Exchangers - Advantages | Applications | Specifications
Titanium Heat Exchanger
Plate and Shell Heat Exchanger - Applications | Specification
Block Welded Heat Exchanger - Applications | Specification