What is an air-cooled cooler

By Air cooling the surface of heat-generating objects such as electronic components of power electronics, combustion engines and air conditioning systems is cooled by air flowing past them.


The air movement necessary for air cooling can be brought about either by convection, blowers or, in the case of vehicles, by the airstream. The object to be cooled is free or is channeled around it. Often the object to be cooled is also provided with cooling fins or a heat sink as a heat exchanger, which allow a greater heat dissipation through a larger surface.

Air cooling in engines

Main article: Cooling (internal combustion engine)

In contrast to water-cooled motors, an air-cooled motor cannot burst due to freezing of the cooling water or the coolant at temperatures below freezing point and cannot boil over at too high temperatures because there is no cooling water or no coolant. Air-cooled engines also have a longer service life than water-cooled ones because they have fewer components at risk of failure (one of the most common reasons for engine damage in water-cooled engines is, for example, a defective cylinder head gasket between the coolant circuit and the combustion chamber). In trucks, the efficiency of air cooling is superior to that of water cooling, which is why trucks with air-cooled engines consume less fuel than trucks with water-cooled engines of the same power.

A fundamental disadvantage of air cooling compared to water cooling is that the heat transfer coefficient between air and a solid is about a factor of 50 to 100 lower than the heat transfer coefficient between water and a solid. Air cooling therefore requires a larger contact area between the two media (which can be increased by a cooling fin if necessary) and higher flow speeds (which can be ensured by a cooling fan if necessary) than water cooling. Since cars with air-cooled engines require a powerful cooling fan, which requires more power than the water pump of a water cooling system, the overall efficiency of air-cooled engines in cars is worse than that of water-cooled engines. Air-cooled internal combustion engines are also generally quite noisy and efficient interior heating is difficult to implement. In addition, the operating temperature and thus also the performance and consumption of an air-cooled engine depend more on the current outside temperature, which is why many air-cooled vehicles still have an oil cooler with a thermostat. In addition, higher temperatures occur with air cooling than with water cooling, which makes compliance with modern exhaust gas regulations more difficult. Air-cooled engines are therefore used less and less in motor vehicles.

Automobiles such as the Porsche 911, the VW Beetle, the Trabant and the Citro├źn 2CV, but also trucks from Magirus-Deutz and Robur were equipped with air-cooled engines. Air-cooled engines are still quite common in motorcycles today. Companies such as Harley-Davidson, Buell, Ducati, Moto Guzzi or BMW have numerous models with air cooling in their current range. Further applications of the air-cooled engine are in propeller aircraft and in RC cars with internal combustion engines.

Air cooling in personal computers

In relation to the size - especially with processors from the class Intel 486/66 - with the technology that is commercially economically available, a large amount of heat is generated. Powerful microchips, as used in current PCs, generate considerable heat loss, which is mainly dissipated by air cooling. The purpose is to prevent thermal overloading of the chips.

Since the entire input power is converted into heat, the operating voltages of the heat-generating components were first reduced. Furthermore, in current processors, parts of the arithmetic unit are reduced in clock frequency or switched off completely when not in use. Nevertheless, the natural heat dissipation through radiation and convection was no longer sufficient, so that the thermally effective surfaces were first cooled by the use of heat sinks and then - because it was still not sufficient - the possible heat dissipation was increased through the use of electrically operated fans (cf. Processor cooler). The most strongly cooled system in PCs is the CPU, but the power supply unit and, for some time now, the processors of graphics cards are also air-cooled. Alternatively, you can also install water cooling in PCs.

Other uses

HiFi amplifiers are also usually air-cooled.

When machining hygroscopic (moisture-absorbing) plastics, air cooling is also used, because normal coolants can dissolve or swell the plastic.

See also

Category: Cooling technology