An anti-ice valve 17HH (37HH) (Ref. 21-61-00) is used to stop (as a back-up) ice formation downstream of the turbine and in the condenser. When a significant pressure drop is sensed the valve opens, tapping hot air from downstream of the flow control valves 8HB (11HB). This hot air is delivered to the turbine which eliminates any ice formation.
Additionally the bypass valves always maintain a minimum air-cycle machine flow to keep the air-cycle machine idling during all pack operation conditions.
R **ON A/C 401-499,
In the air-cycle machine turbine, the high pressure air expands and its kinetic energy drives the air-cycle machine, and the temperature and the pressure decreases. This causes an additional condensation in the air-cycle machine turbine outlet during ground operation and low altitude flight operation. This condensation appears as snow.
The turbine outlet air passing through the condenser is the now conditioned air. It leaves the air cooling system through the pack downstream check valves.
To prevent freezing at low ambient temperatures and to limit high pack discharge temperatures, the water extractor outlet temperature is limited to between a lower limit and 70 DEG.C (158.00 DEG.F). The lower limit depends on the altitude and is:
-5 DEG.C (41.00 DEG.F) between ground and 20000 ft
-0 DEG.C (32.00 DEG.F) to 5 DEG.C (41.00 DEG.F) between 20000 ft and 28000 ft - -30 DEG.C (-22.00 DEG.F) to 0 DEG.C (32.00 DEG.F) between 28000 ft and
39800 ft. Air is bled from the compressor inlet through the bypass valve 10HH (30HH) to the turbine outlet. This modulates pack discharge temperature to the required level, if the limits for the water extractor are not exceeded. It is also used to stop (as a back-up) ice formation downstream of the turbine and in the condenser. When a significant pressure drop is sensed the valve opens, tapping hot air from downstream of the flow control valves 23HB (24HB). This hot air is delivered to the turbine which eliminates any ice formation.
Additionally the bypass valves always maintain a minimum air-cycle machine flow to keep the air-cycle machine idling during all pack operation conditions.
**ON A/C ALL
The ambient ram air for heat exchanger cooling, enters the air cooling system through fully modulating NACA-type inlets. After passing through the primary heat exchanger, the main heat exchanger and the plenum the air is discharged overboard through the ram air outlet. When the aircraft is on the ground, the air-cycle machine fan supplies the cooling airflow. During flight the inlet area is modulated so that the airflow is kept to a minimum. During takeoff and landing, the inlet is fully closed to prevent dirt ingestion and contamination of the heat exchangers. The water injetor 20HM (21HM) sprays the condensed water from the water extractor into the ambient ram airflow to help cooling.
R **ON A/C 001-049, 051-099, 101-149, 151-199, 201-299,
R B. Single Air Condition Pack Mode The aircraft can fly with one air conditioning pack inoperative provided: - FL310 is not exceeded, - the zone controller primary channel is operative, - the HI flow is selected, - the affected PACK 1 or 2 pushbutton switch is in the OFF position and the flow control valve is checked closed on the ECAM system.
R **ON A/C 301-399,
B. Single Air Condition Pack Mode The aircraft can fly with one air conditioning pack inoperative provided: - FL310 is not exceeded, - the zone controller primary channel is operative, - the affected PACK 1 or 2 pushbutton switch is in the OFF position and the flow control valve is checked closed on the ECAM system.
R **ON A/C 401-499,
R R R R R R B. Single Air Condition Pack Mode The aircraft can fly with one air conditioning pack inoperative provided: - one of the two lanes of the applicable ACSC is operative, - the HI flow is selected, - the affected PACK 1 or 2 pushbutton switch is in the OFF position and the flow control valve is checked closed on the ECAM system.
R **ON A/C 001-049, 051-099, 101-149, 151-199, 201-299, 301-399,
C. Heat Exchanger Cooling Mode One air conditioning pack can also be operated on heat exchanger cooling only provided: - the corresponding pack controller is fully operational, - the TAT indication is available, - the affected pack is not operated until the aircraft is airborne, - the TAT is less than 12 Deg C and the pack outlet temperature indication is available.
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