Do Aeroplane really needs air conditioning at an altitude of 10 KM ??

Do Aeroplane really needs air conditioning at an altitude of 10 KM ??


Aeroplanes generally fly at 10KM above earth's surface and at that altitude temperatures are less than -50 Degree centigrade. But still, it requires air conditioning because of the following reasons:

  • At 10KM above earth's surface pressure is at 0.1 atm. At such low pressures, human lungs cannot perform respiration easily. So pressurisation of air is required through conditioning
  • Air will be rammed into the jet through small openings near wings from a 1000km/hr moving aeroplane. This ramming of air causes a lot of temperature rise around 30 deg centigrade.
  • There is a lot of solar radiation at that altitude and the heat gain due to solar need to be taken care of.
  • And generally, in a domestic plane, average flyers will be around 150 and if we consider 100 watts per person as heat dissipation then the heat load is around 5 TR
  • Apart from all the above loads, aeroplane involves a lot of electronic control circuitry that dissipates a reasonably high amount of heat and this also will add up to the heat load
In order to take care of all heat loads or heat gains and pressure regulation, aeroplane requires air conditioning system. Conditioning of air doesn't be only cooling instead it covers pressurisation, filtration, acoustic correction etcetera.

Generally, air refrigeration systems are used in air crafts because of many advantages like
  • Low cost as air is free and cheap
  • Air is inert and safe
  • Operating pressures are low
  • Easier to operate
  • No secondary heat transfer medium as air itself can be directly circulated 
  • No need of specialised compression systems as the turbo compressor in the gas engine of aircraft can do the required job.

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