The main working area for aircraft is thousands of metres above sea level, where changes in thermal conditions require the use of appropriate temperature control systems; but also on the ground...
Heat and temperature are two concepts so closely related that colloquially they can be used as synonyms, but properly speaking, whereas heat and temperature are so closely related that colloquially they can be used as synonyms. temperature quantifies the speed or energy with which the atoms move of matter, the heat is the transfer of this energy between two materials due to the fact that they communicate with each other and are at different temperatures.
An object that is at a higher temperature than that for which it was designed will sooner or later present a problem in its operation. For example, in electronic equipment, the path of the electrons would be uncontrolled and the signals would not be transmitted as expected. On the other hand, extreme overheating can cause a material to change from a solid to a liquid, change of status known as fusion. It occurs when atoms move so much that they become detached from each other. This happens in some aircraft or components that pass through the atmosphere at an inappropriate angle or speed, usually because they have lost control of them, and inevitably results in their destruction.
As far as living beings are concerned, we also need to keep temperature levels under control so that our metabolism does not suffer. Achieving this comfort is a basic requirement for passenger aircraft.. However, occasionally there are reports of problems with a pet that may have been transported in a non-refrigerated, and therefore unsuitable, area such as the cargo hold.
As can be deduced, it is necessary to have various cooling systems to manage the heat and avoid problems resulting from overheating. A possible classification could be as follows:
Cabin refrigeration
La mayoría de los aviones vuelan a una altura considerable de miles de kilómetros y disponen de pressurised cabins para compensar el menor nivel de oxígeno en el aire. A esas altitudes el aire exterior además es frío, decenas de grados bajo cero, por lo que es necesario crear una atmósfera interior con un control de temperatura semejante al sistema de aire acondicionado que tenemos en nuestras casas, pero con la gran diferencia de que el aire no proviene de una mera unidad exterior situada en una terraza o balcón, sino que se utiliza un complejo inlet air compression system from the engines.
Cooling of the structure
The structure of the aircraft usually shall not require a specific temperature protection system, ya que el rango de funcionamiento del material suele ser bastante elevado. Solo algunas aeronaves estratosféricas, como los transbordadores espaciales, necesitarán protecciones térmicas adicionales. Existen diversos mecanismos, como el de añadir placas especiales al fuselaje, que sirven para soportar las altas temperaturas que se producen en la reentrada debido a la fricción con la atmósfera.
Equipment cooling
There are two ways of cooling equipment, blowing air with supply fans or extracting it with so-called extraction fans. En este caso, el principio físico es aprovechar la convección térmica para que el aire absorba el calor de los objetos que rodean. El hecho de usar ventiladores provoca que haya más cantidad de aire que no haya sido calentado alrededor de estos.
On the other hand, it should be mentioned that water is an even better coolant than air gracias a su mayor calor específico, que es la cantidad de energía que puede absorber antes de incrementar su temperatura. Por eso se usa para refrigerar los coches y también ordenadores. En los automóviles, la razón por la que se usa mezclado con otros aditivos es únicamente para evitar su congelación a temperaturas inferiores a 0 °C. Pero usarlo en los aviones es un problema debido a su mayor peso, un parámetro muy a tener en cuenta en este sector.
Por último, cabe destacar que una utilidad adicional de los sistemas de gestión del calor que se están desarrollando y experimentando actualmente, aparte de la de refrigeración, es la de intentar reuse of thermal energy by converting it into electrical energy. Fuel economy is another highly appreciated value in this industry and there is no doubt that we will see this technology implemented within a few years.
