HVAC on commercial aircraft
Basically compress the crap out of the air, cool the hot compressed air down with outdoor air, separate the condensation from it, then feed it out through the air distribution system, where it magically becomes cold as it expands.
No refrigerant cycle needed.
Works great at 30k, where the outdoor air is very cold all the time.
Not so great on the ground, but still acceptable.
Sucks bawlz when your flight gets delayed, after boarding, and the pilot starts backing off the APU, and shutting stuff down to conserve fuel.
The air cycle pack system is very common on transport category aircraft.
Usually, it works great.
[Avatar photo from a Florida training accident. Everyone walked away.]
2 Tim 3:16-17
RSES CMS, HVAC Electrical Specialist
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The cooling effect comes from the discharge air at the expansion turbine.
Originally Posted by mark beiser
I just gotta find the control panel on the 737-700... Those Copa Air crazies keep the cabin WAY too cold