OT: Airliner air conditioning, I know someone here will know this... Options

[URY914]

On a car the a/c compressor runs off the engine.
In a house the a/c compressor is run by an electric motor.

(you can figure out my next question, can't you?)

How is the compressor on a airliner (737, 747,etc) powered?
I've never noticed a big v-belt on the engine before.

If it is powered by a electric motor, if so how is the generator powered? Is there some type of power take off from jet engines?

Thanks,

Paul

[Dominic]

It takes air off the compressor section. Depending on what stage it is coming off of it could be upwards of 490 Deg. F( if over that you should get a pack trip) It then goes into a precooler at the pylon. From there it goes into two big heat exchangers and an air cycle mechiene ( think a big turbo) and past the 35 degree valve then into a water seperator. The 35 deg. valve injects hot air back in so the water seps dont freeze.After that it goes into the distribution bay at the back of the forward bag bin then off to cool little Timmy on his way to Grandmas. The out flow valve at the rear closes to start presureization. but as you climb the pres actually decreases from ground pres. The cabin altitude will climb to aprox 10000 feet while the airframe is at 30000+ when you come down it increases the cabin pres to field elevation. That is basicaly it. Hope this helps.

(IMG:style_emoticons/default/agree.gif) Except for the cabin altitude part....35000 FT at 8.2 psi differential pressure is around 5500 FT cabin altitude.
I spent a lot of hours in the air controlling the pressurization (IMG:style_emoticons/default/biggrin.gif)