Industrial heaters are used to covert energy from a fuel or energy source to thermal energy in a system, process stream or closed environment. The process by which thermal energy is transformed from an energy source to a system can be described as heat transfer.
There are three fundamental methods of heat transfer: conduction, convection and radiation. Industrial heaters use one or a combination of these three methods to transfer heat.
Thermal conduction is the transfer of thermal energy across a solid object. When an energy source is directly applied to a solid object the molecules in that substance start to vibrate at a higher frequency and transfer that energy to the adjoined molecules.
Convection is a method of heat transfer where thermal energy is carried through a fluid or medium. The fluid or medium creates a convection current that is either forced or free flowing. In forced flow convection the medium is circulated by either a fan or pump. In free flowing systems the convection cycle is solely dependent on temperature changes and density gradients.
Thermal radiation is an indirect method of heat transfer. In this method thermal energy is transferred through electro-magnetic waves. Since these waves have negligible mass the transfer of heat requires no physical contact between substances and the waves are free to pass through empty space until they make contact with a physical substance. When the waves are absorbed we experience an excited state and the affected molecules begin to vibrate at a higher frequency. The resultant effect of absorption and vibration frequency is heat or more fundamentally, an increase in temperature.