Aircooling

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Air cooling is one method of dissipating heat. It works by making the object to be cooled have a larger surface area or have an increased flow of air over its surface, or both. An example of the former is to add fins to the surface of the object, either by making them integral or by attaching them tightly to the object's surface (to ensure efficient heat transfer). In the case of the latter it is done by using a fan blowing air into the object one wants to cool. In many cases the addition of fins adds to the total volume of material making a heatsink that makes for greater efficiency in cooling.

In all cases the air has to be cooler than the object or surface from which it is expected to remove heat because thermodynamics says that heat moves from higher to lower levels.

1 Examples
2 Exceptions
3 See also
4 External links

[edit] Examples

[edit] Vehicles

Air is mainly used for cooling internal combustion engines (ICE), particularly those powering aircraft, because it is a readily available fluid and is often at a suitable temperature to be used efficiently. While many such ICE are called "liquid cooled" the cooling liquid is usually cooled by air passing through a radiator or heat exchanger. Examples of direct aircooling in automobiles are the flat or boxer engines such as in the pre-1996 model Porsche 911, the VW Beetle, the Chevrolet Corvair, the Citroën 2CV, the 247 BMW and some early Honda keicars.

[edit] Turbines

Gas turbine engines (e.g. turbojets, turbofans, etc) incorporate turbines, which are exposed to the hot gases exiting the combustion chamber. Where necessary, relatively cold air is bled from the compression system and used to cool the turbine blades and vanes, to prevent them from melting.

[edit] Electronics

Its use is widespread in computers and CPU cooling, where the computer processors produce large quantities of heat that, if not dissipated, could damage the CPU and other electronic components. In this case air has the advantage of being a good insulator too. However, in the future, new processors might generate too much heat to be dissipated through direct air cooling and it would follow that such direct cooling for computers and their components will become obsolete.

[edit] Industries

A very large number of industrial processes use air as a cooling medium, either directly or indirectly. A very common process is air conditioning where the air in a room or a whole building is cooled so that a comfortable human environment is obtained and the air in contact with the people is able to carry away the heat generated by the body and by such as office or kitchen equipment. Often the air has been cooled by chilled water or brine and the heat transferred to that meduim is transported outside the building where, often, fan-driven water-to-air heat exchanging is again effected to reject the heat into the atmosphere. A common sight around, for example, power stations are the large waisted concrete towers that emit steam more or less constantly. These are, in part, using air cooling on a grand scale.

[edit] Exceptions

Ships are one of the few complex power generating systems that do not use air cooling very much at all. Most of their heat goes directly into the water.