For any modern aircraft to fly at high altitudes, it must be equipped with an air conditioning and pressurization system, which provides a convenient environment for its passengers. The human body is unable to withstand the effects of a low-pressure atmosphere, which makes the A/C and pressurization system a vital component of modern flight.
JAR-OPS 1.770 and 1.775 by the JAA, along with other regulatory authorities, have established a minimum pressurization requirement for all modern aircraft which must be satisfied before an aircraft can fly.
Air Conditioning System on the Airbus A 320
Aircraft A/C systems are more or less similar on all modern airplanes. However, the following explanation of the system is specific to the A 320 Airbus. The system is fundamentally comprised of air conditioning packs, a pack flow control valve, a by-pass valve, pack controllers, and a mixing unit.
These components provide conditioned air via the following step by step process:
- First, outside air enters the airplane engine.
- Next, compressors within the engine compress this low-density air.
- Hot compressed air from the compressor (bleed air) is then transported via ducts to the A/C packs.
- Prior to entering the air conditioner units, the bleed air passes through the pack flow control valve, which regulates the flow of air entering the conditioning packs.
- Within the A/C unit, two air-to-air heat exchangers are installed that supply outside air via a pack inlet scoop and the air exits through an outlet duct.
- As the cold air exits from the conditioning pack, it is mixed with warm air.
- The desired air temperature is achieved by regulating the amount of hot air mixed with the cold conditioned air exiting from the packs through a by-pass valve.
- The regulated air is then fed to a mixing unit which transports the air further on into the cabin and the cockpit.
- The by-pass valve, pack flow control valve, inlet scoop and outlet duct are all operated by, and connected to, a pack controller.