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Now we have cold air that we need to prepare as it is very cold and to distribute this air all over the cabin.

The cold air produced by the cooling packs ,described previously, will be mixed with air coming from the cabin and thus at little higher temperature than what is required.

The distribution and zone temperature control system will control this phase and provide air at the right temperature where required.

 

THE FIRST STEP OCCURS IN THE MIXING CHAMBER

This is often a large housing with the following pneumatic connections:

INLETS :
a) Cold and fresh air from the cooling packs

b) Air coming from the cabin.This design feature is called " recirculation " and the main advantage is to save fuel consumed by the aircraft engine as the air flow bled on the engines is lower.

OUTLETS :
distribution ducts toward the various cabin zones.

 

THE SECOND AND FINAL STEP IS THE AIR DISTRIBUTION AND THE TEMPERATURE CONTROL IN EACH AREA OF THE AIRCRAFT CABIN.

During some flight phase, it is necessary to heat the cabin air ; this is carried out downstream the mixing chamber with hot air bled upstream the cooling packs.
This hot air is mixed in the various ducts supplying the different cabin areas with air coming from the mixing chamber

THEN the air is pushed inside the distribution ducts to the various cabin zones: cockpit, cabin areas, toilets, ... .

 

This sophisticated function which consists to supply each zone with the air at the required temperature is controlled by a feed back system with computers and temperature sensors for each zone.

 

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bleed air system / air cooling system / zone temperature control system / cabin pressure control system