How does the aircraft' air conditioning works?

Question

I always wondered how does it work, especially on big passenger jets flying as high as 43000' is it similar to the conventional systems at buildings and cars? if not what are the differences?

Answer 1

No, the airconditioning system on most jet or turboprop aircraft is unlike any ground-based AC system. It uses a piece of equipment called an Air Cycle Machine.

This machine takes compressed air from the engines, called bleed air, and runs it through a turbine similar to a turbo charger. The wheel in the turbine is connected to a fan assembly that blows ambient air over a radiator at the exit from the turbine.

Between the energy extracted by the turbine and the cooling effect of the fan, the bleed air temperature drops from around 400 degrees F to slightly above freezing. This cooled air then passes through a compartment called a coalescer that removes most of the moisture from the air.

Finally, the air is mixed with a bit of raw bleed air from the engines and piped throughout the aircraft.

If you've ever been on an airliner that started throwing snow or dense fog out of the AC vents, it means that the coalescer has failed in the AC system. The coalescer is nothing more than a cone-shaped cloth bag and they do rupture sometimes. If conditions are right, usually at lower altitudes, the system can throw snow or thick fog. It's disconcerting, but quite harmless.

Answer 2

The two types of air conditioning systems you'll find on aircraft are vapor cycle machines and air cycle machines. Vapor cycle machines use Freon, just like car's and home A/C's. Air cycle machines create cold air by compressing engine bleed air and running it through an expansion turbine.

Answer 3

On most aircraft the air is heated by compression from the engines. Then sent to tthe airconditioning unit where it is cooled or heated by compression or expansion, as well as cooled by outside temp. This is then fed into the a/c to be used for compressing the aircraft and temp control

Answer 4

it depends on the plane . but i know for a fact that on some miltary birds they use whats called a ram air .system . in which air is forced through a plennum and a turbine assemby and comes out cold enough to freeze.

Answer 5

Basically a coalescer is a sock that catches moisture.

Answer 6

Wow its so nice to read the Answers, thanx to all, the Question asker and to all who Answer.