Heat dispersion in electronic and mechanical systems is a key factor in the thermal planning of the system. Heat sources within a system can be varied and different, requiring creative solutions for dispersing the heat. An important and irreplaceable tool in this regard is thermal analysis, in which heat sources and their influence on their surroundings are examined. There are many variances of heat source and each one requires a different mechanism of transfer: conduction, convection and radiation.

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Conductivity

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Transmission of heat through conduction occurs in an object with no moving parts. However, the heat potential moves through the entire object. For example, a metal heat with one hot edge, and one cold. If the sheet is left, with no external influence, the heat will move to the cold edge until the temperature is the same over the entire plate. This “movement” is the potential heat of the sheet over its entirety.

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Convection

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Heat transfer by convection, consists of heat transfers between solid and liquid through the boundary layers adjacent to the solid as well as heat transfer in the flow itself (diffusion).

There are two types of convection: forced convection and natural convection. Forced convection occurs under an initiated flow such as a pump or blower. Natural convection occurs through natural flow without any external constraint.

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Radiation

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Heat transfer by radiation is essentially electromagnetic radiation emitted from objects. Electromagnetic radiation results from charges moving in space, and thus every object emits such radiation. Examples of electromagnetic radiation include sunlight, ultraviolet light, and infrared light. Electromagnetic radiation has unique properties in that surface properties affect the radiation properties, where a key determinant of the radiation is density. Radiation (including solar) can be concentrated in a very limited area for example by mirrors as opposed to convection or conduction.

A thermal system combines all three heat transfer mechanisms: conduction, transport and radiation, between different materials with various sizes and properties. For example: a chip with a heat sink -  in this system there is transmission throughout the system, a chip glue and a heat sink. Between the system and the environment there is convection and radiation.

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Examining heat transfer in a given system requires defining all the relationships of the components between themselves and between the environment to accurately describe the problem numerically.