DC-10Tech From United States of America, joined Jun 2001, 298 posts, RR: 3 Reply 5, posted (12 years 6 months 6 days 21 hours ago) and read 14148 times:
The Cabin Air comes from the engines. It is bled from the engine compressors and ducted through the air conditioning system and then into the plane. The air being forced into the cabin is let out slowly through the pressurization outflow valve. The cabin pressure is then maintained by regulating how fast the air is let out of the cabin.
JETPILOT From United States of America, joined May 1999, 3130 posts, RR: 30 Reply 6, posted (12 years 6 months 6 days 21 hours ago) and read 14148 times:
Air for Pneumnatic Air Conditioning operation is bled off from various stages of the engines compressors. This compressed and very hot air (500 degrees C) is then sent through a pre cooler (heat ecxhanger) to lower the temperature before sending it into the PAC compressor.
The PAC turbo compressor compresses the pre cooled air heating it up again. It then goes through another heat exchanger dropping the temperature before entering an expansion turbine. As the air expands in the expansion turbine it cools very rapidly. This cold air leaves the expansion turbine and supplies the cockpit temperature controlled mix valve with cold air.
The hot air for the mix valve comes directly off the engine bleed after it has ben pre cooled. The wrarm air supplied to the mix valve is bled after the PAC compressor but before the expanson turbine. The position of this mix valve determines the temperature of the air enetering the cabin.
Speedbird001 From United Kingdom, joined May 2000, 30 posts, RR: 0 Reply 7, posted (12 years 6 months 6 days 9 hours ago) and read 14138 times:
This subject has been discussed many times previously - try searching the forums. Also, alot if interesting info on the AC systems on Boeing A/craft can be found on http://www.boeing.com/commercial/cabinair/
A simple description can be found, but if you go to "System description (PDF)" link, a PDF file explains the system with the help of diagrams. - Very good explinations.
Hope this helps
Concorde speedbird 001 - fly again soon