Air conditioning is provided in passenger aircraft for the comfort of passengers, to pressurise, heat, cool, and ventilate the aircraft cabin. The air conditioning system is supplied by air processed through two packs which regulate airflow and temperature as required. Airplane air conditioning system mixes hot and cold air to achieve the desired temperature in the cockpit and cabin.
It uses bleed air from Engine or APU to provide conditioned air to the cabin with sufficient pressure and flow to maintain cabin pressurisation and a temperature controlled environment throughout the operating envelope of the aircraft.
It is a little known fact that PACK is an acronym for Pneumatic Air Conditioning Kit.
The basic air conditioning system in use in A320 is fan turbine (turbo fan) which uses bleed air.
The basic airflow through the pressurised part of the fuselage starts with the pneumatic system.
Hot, high pressure air is supplied to two packs. The packs are responsible for basic temperature regulation.
From the packs the air is distributed throughout the aircraft.
The pressurisation system controls the airflow overboard to maintain the cabin pressurisation within safe limits.
- Requirement of fresh air: Fresh air must be provided 1lbs per seat per minute and not less than 0.5lbs in case of emergency.
- Temperature: Should be maintained between 18°c to 24°c.
- Relative Humidity: The RH of the cabin be should be maintained at approx 30%.
- Contamination: Co particle contamination should not be more than 1 in 20,000.