DOC AIRBUS | AMM A320FAIR COOLING SYSTEM - DESCRIPTION AND OPERATION
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1. General
The two air conditioning packs decrease the temperature and the water contained in the hot bleed air from the pneumatic system. Heat exchangers decrease the temperature of the air. An air-cycle machine first compresses the air and then expands it. A condenser condenses the water in the air and a water extractor removes the water.
** ON A/C NOT FOR ALL The two air conditioning packs decrease the temperature and the water contained in the hot bleed air from the pneumatic system. Heat exchangers decrease the temperature of the air. An air-cycle machine first compresses the air and then expands it. A condenser condenses the water in the air and a water extractor removes the water.
2. Component Location
Air Cooling System - Component Location ** ON A/C NOT FOR ALL
Air Cooling System - Component Location ** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL Air Cooling System - Component Location ** ON A/C NOT FOR ALL Air Cooling System - Component Location ** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
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| 10HM | PACK 1-AIR CONDITIONING | 191KB | 191 | 21-52-41 | |
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| 10HM1 | MACHINE-AIR CYCLE | 191KB | 191 | 21-52-21 | |
| 10HM2 | CONDENSER | 191KB | 191 | 21-52-32 | |
| 10HM3 | REHEATER | 191KB | 191 | 21-52-31 | |
| 10HM5 | PLENUM CHAMBER | 191KB | 191 | 21-52-22 | |
| 10HM6 | HEAT EXCHANGER-PRIMARY | 191KB | 191 | 21-52-25 | |
| 10HM7 | HEAT EXCHANGER-MAIN | 191KB | 191 | 21-52-26 | |
| 10HM8 | EXTRACTOR-WATER | 191KB | 191 | 21-52-16 | |
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| 10HM | PACK 1-AIR CONDITIONING | 191 | 21-52-41 | ||
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| 11HM | PACK 2-AIR CONDITIONING | 192KB | 192 | 21-52-41 | |
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| 11HM1 | MACHINE-AIR CYCLE | 192KB | 192 | 21-52-21 | |
| 11HM2 | CONDENSER | 192KB | 192 | 21-52-32 | |
| 11HM3 | REHEATER | 192KB | 192 | 21-52-31 | |
| 11HM5 | PLENUM CHAMBER | 192KB | 192 | 21-52-22 | |
| 11HM6 | HEAT EXCHANGER-PRIMARY | 192KB | 192 | 21-52-25 | |
| 11HM7 | HEAT EXCHANGER-MAIN | 192KB | 192 | 21-52-26 | |
| 11HM8 | EXTRACTOR-WATER | 192KB | 192 | 21-52-16 | |
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| 11HM | PACK 2-AIR CONDITIONING | 192 | 21-52-41 | ||
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| 15HM | P1 CHECK VALVE DOWNSTREAM | 191BB | 191 | 21-52-43 | |
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| 15HM | P1 CHECK VALVE DOWNSTREAM | 191 | 21-52-43 | ||
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| 16HM | P2 CHECK VALVE DOWNSTREAM | 138 | 21-52-43 | ||
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| 20HM | P1 WATER INJECTOR | 191KB | 191 | 21-52-42 | |
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| 20HM | P1 WATER INJECTOR | 191 | 21-52-42 | ||
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| 21HM | P2 WATER INJECTOR | 192KB | 192 | 21-52-42 | |
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| 21HM | P2 WATER INJECTOR | 192 | 21-52-42 | ||
3. System Description
Air Cooling System - Schematic ** ON A/C NOT FOR ALL
Air Cooling System - Schematic ** ON A/C NOT FOR ALL
The air conditioning packs 10HM (11HM) are identical and are installed in the unpressurized area of the belly fairing in front of frame 40.
The air conditioning pack 10HM (11HM) consists of:
Air Cooling System - Schematic ** ON A/C NOT FOR ALL Air Cooling System - Schematic ** ON A/C NOT FOR ALL The air conditioning pack 10HM (11HM) consists of:
- an air-cycle machine,
- a high-pressure water extractor,
- a reheater,
- a condenser,
- a primary heat exchanger,
- a main heat exchanger,
- a fan plenum,
- for various other components of the pack refer to chapter 21-61-00.
A. Primary Heat Exchangers
The primary heat exchangers 10HM6 (11HM6) are installed in the ram air system between the fan plenums and the main heat exchanger. Ram air flows through the heat exchangers and decreases the temperature of the hot bleed air from the pneumatic system.
The primary heat exchangers 10HM6 (11HM6) are installed in the ram air system between the fan plenums and the main heat exchanger. Ram air flows through the heat exchangers and decreases the temperature of the hot bleed air from the pneumatic system.
B. Air-Cycle Machines
The air-cycle machines 10HM1 (11HM1) are installed between the plenums and the condensers. Air enters the compressor from the primary heat exchanger and is compressed. The pressure and temperature increase. The air then flows to the main heat exchanger. Air enters the turbine from the reheater and is expanded. The pressure and temperature decrease. The air then flows to the condenser. The expansion of the air in the turbine turns the turbine wheel, the compressor wheel and the fan wheel. The fan wheel gives a flow of ram air through the ram air system if there is no ram air effect (on the ground).
The air-cycle machines 10HM1 (11HM1) are installed between the fan plenum and the condenser.
The Air cycle machine is a single 3-wheel air bearing machine. All three wheels (compressor wheel, turbine wheel, fan wheel) are connected by an rotating shaft assembled in one housing.
Bleed air comes from the primary heat exchanger and is compressed in the compressor. The pressure and temperature increase. The air then is cooled in the main heat exchanger. To get a higher expansion ratio in the turbine, air enters the turbine from the reheater and is expanded. The pressure and temperature decrease. The air then flows through the condenser. the radial-inward flow expansion turbine cools the bleed air and provides power to drive the compressor and the cooling air fan. The fan wheel gives a cooling flow through the primary and main heat exchanger. In flight a flow is additionally forced by ram air pressure.
The air-cycle machines 10HM1 (11HM1) are installed between the plenums and the condensers. Air enters the compressor from the primary heat exchanger and is compressed. The pressure and temperature increase. The air then flows to the main heat exchanger. Air enters the turbine from the reheater and is expanded. The pressure and temperature decrease. The air then flows to the condenser. The expansion of the air in the turbine turns the turbine wheel, the compressor wheel and the fan wheel. The fan wheel gives a flow of ram air through the ram air system if there is no ram air effect (on the ground).
The air-cycle machines 10HM1 (11HM1) are installed between the fan plenum and the condenser.
The Air cycle machine is a single 3-wheel air bearing machine. All three wheels (compressor wheel, turbine wheel, fan wheel) are connected by an rotating shaft assembled in one housing.
Bleed air comes from the primary heat exchanger and is compressed in the compressor. The pressure and temperature increase. The air then is cooled in the main heat exchanger. To get a higher expansion ratio in the turbine, air enters the turbine from the reheater and is expanded. The pressure and temperature decrease. The air then flows through the condenser. the radial-inward flow expansion turbine cools the bleed air and provides power to drive the compressor and the cooling air fan. The fan wheel gives a cooling flow through the primary and main heat exchanger. In flight a flow is additionally forced by ram air pressure.
C. Main Heat Exchangers
The main heat exchangers 10HM7 (11HM7) are installed in the ram air systems upstream of the primary heat exchangers. Ram air flows through and decreases the temperature of the hot air from the compressor of the air-cycle machine.
The main heat exchangers 10HM7 (11HM7) are installed in the ram air systems upstream of the primary heat exchangers. Ram air flows through and decreases the temperature of the hot air from the compressor of the air-cycle machine.
D. Reheaters
The reheaters 10HM3 (11HM3) are installed between the main heat exchangers and the condensers. The hot air from the main heat exchanger increases the temperature of the cold air from the water extractor.
The reheaters 10HM3 (11HM3) are installed between the main heat exchangers and the condensers. The hot air from the main heat exchanger increases the temperature of the cold air from the water extractor.
E. Condensers
The condensers 10HM2 (11HM2) are installed between the air cycle machines and the mixer unit. The cold air from the turbine of the air cycle machine decreases the temperature of the hot air from the reheater. The temperature of the hot air decreases to less than its dew point and the water in the air condenses.
The condensers 10HM2 (11HM2) are installed between the air cycle machines and the mixer unit. The cold air from the turbine of the air cycle machine decreases the temperature of the hot air from the reheater. The temperature of the hot air decreases to less than its dew point and the water in the air condenses.
F. Water Extractors
The water extractors 10HM8 (11HM8) are installed between the condensers and the reheaters. They remove the water that condenses in the condensers. The condensed water drains to the applicable water injector 20HM (21HM).
The water extractors 10HM8 (11HM8) are installed between the condensers and the reheaters. They remove the water that condenses in the condensers. The condensed water drains to the applicable water injector 20HM (21HM).
G. Downstream Check Valves
The downstream check valves 15HM (16HM) are installed between the condensers and the mixer unit. Air flows through the downstream check valves to the mixer unit. The downstream check valves close if the air flows in the opposite direction. This is to prevent leakage from the pressurized zone on case of failures of the air conditioning system.
The downstream check valves 15HM (16HM) are installed between the condensers and the mixer unit. Air flows through the downstream check valves to the mixer unit. The downstream check valves close if the air flows in the opposite direction. This is to prevent leakage from the pressurized zone on case of failures of the air conditioning system.
H. Fan Plenums
The fan plenums 10HM5 (11HM5) are installed in the ram air system and are connected to the air-cycle machines. In flight, mainly the ram air effect causes air to flow through the ram air system. The air-cycle machine fan is in bypass but still rotating by turbine air expansion.
The fan plenums 10HM5 (11HM5) are installed in the ram air system and are connected to the air-cycle machines. In flight, mainly the ram air effect causes air to flow through the ram air system. The air-cycle machine fan is in bypass but still rotating by turbine air expansion.
4. Component Description
A. Air Conditioning Packs FIN: 10-HM FIN: 11-HM
The air conditioning packs 10HM (11HM) are identified as PACK 1 and PACK 2 to correspond with the pneumatic manifolds. Both packs are installed in the unpressurized area of the belly fairing between frames 35 and 41. The air conditioning pack supplies the means of cooling the hot bleed air taken from the pneumatic manifold. This is done with the primary heat exchanger, main heat exchanger and a turbine and compressor in a boot-strap air-cycle machine. The turbine supplies shaft power to drive the compressor and fan. On the ground the fan draws ambient air through the primary heat exchanger and the main heat exchanger for cooling.
For pack temperature control functions refer to chapter 21-61-00.
Air Cooling System - Component Location ** ON A/C NOT FOR ALL
Air Cooling System - Component Location ** ON A/C NOT FOR ALL
The air conditioning packs 10HM (11HM) are identified as PACK 1 and PACK 2 to correspond with the pneumatic manifolds. Both packs are installed in the unpressurized area of the belly fairing between frames 35.8 and 41. The air conditioning pack supplies the means of cooling the hot bleed air taken from the pneumatic manifold. This is done with the primary heat exchanger, main heat exchanger and a turbine and compressor in a boot-strap air-cycle machine. The turbine supplies shaft power to drive the compressor and fan. On the ground the fan draws ambient air through the primary heat exchanger and the main heat exchanger for cooling.
For pack temperature control functions refer to chapter 21-61-00.
The air conditioning packs 10HM (11HM) are identified as PACK 1 and PACK 2 to correspond with the pneumatic manifolds. Both packs are installed in the unpressurized area of the belly fairing between frames 35 and 41. The air conditioning pack supplies the means of cooling the hot bleed air taken from the pneumatic manifold. This is done with the primary heat exchanger, main heat exchanger and a turbine and compressor in a boot-strap air-cycle machine. The turbine supplies shaft power to drive the compressor and fan. On the ground the fan draws ambient air through the primary heat exchanger and the main heat exchanger for cooling.
For pack temperature control functions refer to chapter 21-61-00.
The air conditioning packs 10HM (11HM) are identified as PACK 1 and PACK 2 to correspond with the pneumatic manifolds. Both packs are installed in the unpressurized area of the belly fairing between frames 35 and 41. The air conditioning pack supplies the means of cooling the hot bleed air taken from the pneumatic manifold. This is done with the primary heat exchanger, main heat exchanger and a turbine and compressor in a boot-strap air-cycle machine. The turbine supplies shaft power to drive the compressor and fan. On the ground the fan draws ambient air through the primary heat exchanger and the main heat exchanger for cooling.
For pack temperature control functions refer to chapter 21-61-00.
Air Cooling System - Component Location ** ON A/C NOT FOR ALL Air Cooling System - Component Location ** ON A/C NOT FOR ALL For pack temperature control functions refer to chapter 21-61-00.
The air conditioning packs 10HM (11HM) are identified as PACK 1 and PACK 2 to correspond with the pneumatic manifolds. Both packs are installed in the unpressurized area of the belly fairing between frames 35 and 41. The air conditioning pack supplies the means of cooling the hot bleed air taken from the pneumatic manifold. This is done with the primary heat exchanger, main heat exchanger and a turbine and compressor in a boot-strap air-cycle machine. The turbine supplies shaft power to drive the compressor and fan. On the ground the fan draws ambient air through the primary heat exchanger and the main heat exchanger for cooling.
For pack temperature control functions refer to chapter 21-61-00.
B. Air-Cycle Machine
The main component of the air-cycle machine is a rotating shaft. A turbine, a compressor and a fan are mounted along the shaft. The shaft rotates on two self-acting foil-air bearings, a double self-acting air-thrust bearing takes the axial thrust loads. Air tapped from the turbine inlet, is used to cool the bearing and then discharged into the ram airflow. Labyrinth seals reduce air leakage between static and rotating parts. The light-alloy turbine is supplied with air through a stainless-steel nozzle and a light-alloy scroll. In case of turbine break up, the stainless-steel nozzle acts as a containment ring. The light-alloy centrifugal compressor is mounted in the center of the rotating shaft. Air is supplied from a light-alloy scroll, an outer scroll has a stainless-steel diffuser. In case of a compressor break up, the stainless-steel diffuser acts as a containment ring. Fan air is discharged through a conical nozzle, this gives a jet-pump effect in the fiberglass plenum diffuser. The primary heat exchanger outlet is connected to the discharge ram airflow through the fiberglass diffuser.
The air-cycle machine has a de-icing system at the turbine outlet. Hot high-pressure air is tapped from the compressor scroll through a duct. It circulates through the annulus turbine outlet to prevent ice formation at the turbine outlet. The air, after thermal exchange, is returned to the compressor intake through a duct.
The main component of the air-cycle machine is a rotating shaft. A turbine, a compressor and a fan are mounted along the shaft. The shaft rotates on two self-acting foil-air bearings, a double self-acting air-thrust bearing takes the axial thrust loads. Air tapped from the turbine inlet, is used to cool the bearing and then discharged into the ram airflow. Labyrinth seals reduce air leakage between static and rotating parts. The light-alloy turbine is supplied with air through a stainless-steel nozzle and a light-alloy scroll. In case of turbine break up, the stainless-steel nozzle acts as a containment ring. The light-alloy centrifugal compressor is mounted in the center of the rotating shaft. Air is supplied from a light-alloy scroll, an outer scroll has a stainless-steel diffuser. In case of a compressor break up, the stainless-steel diffuser acts as a containment ring. Fan air is discharged through a conical nozzle, this gives a jet-pump effect in the fiberglass plenum diffuser. The primary heat exchanger outlet is connected to the discharge ram airflow through the fiberglass diffuser.
The air-cycle machine has a de-icing system at the turbine outlet. Hot high-pressure air is tapped from the compressor scroll through a duct. It circulates through the annulus turbine outlet to prevent ice formation at the turbine outlet. The air, after thermal exchange, is returned to the compressor intake through a duct.
C. Water Extractor
The water extractor is made from light alloy, and contains static swirl vanes and a water drain inside a body. Swirl vanes centrifuge the water droplets in the air to the inner surface of the water extractor body. The water collects at the lowest point of the body. It is then drained to ducts which leads to the water injectors 20HM (21HM) which spray the water into the ram airflow. This helps the cooling capacity through the process of evaporation. The water extractor is installed at the high-pressure outlet of the condenser.
The water extractor is made from light alloy, and contains static swirl vanes and a water drain inside a body. Swirl vanes centrifuge the water droplets in the air to the inner surface of the water extractor body. The water collects at the lowest point of the body. It is then drained to ducts which leads to the water injectors 20HM (21HM) which spray the water into the ram airflow. This helps the cooling capacity through the process of evaporation. The water extractor is installed at the high-pressure outlet of the condenser.
D. Reheater
The reheater, which is made of aluminum-alloy, is a plate and fin type of single crossflow configuration.
The reheater, which is made of aluminum-alloy, is a plate and fin type of single crossflow configuration.
E. Condenser
The condenser, which is made of aluminium-alloy, is a tubular heat exchanger with a tube-to-tube discharge.
The condenser, which is made of aluminium-alloy, is a tubular heat exchanger with a tube-to-tube discharge.
F. Primary Heat Exchanger
The primary heat exchanger, which is made of aluminum alloy, is a plate and fin type of single-pass crossflow configuration.
The primary heat exchanger, which is made of aluminum alloy, is a plate and fin type of single-pass crossflow configuration.
G. Main Heat Exchanger
The main heat exchanger, which is made of aluminum-alloy, is a plate and fin type, of counterflow configuration. The heat exchanger is installed between the air-cycle machine compressor and turbine, the cooling agent is ambient ram air.
The main heat exchanger, which is made of aluminum-alloy, is a plate and fin type, of counterflow configuration. The heat exchanger is installed between the air-cycle machine compressor and turbine, the cooling agent is ambient ram air.
H. Check-Valve Pack Downstream
The pack downstream check valve 15HM (16HM) is a 6 in. (152.3997 mm), pneumatically operated, single spring loaded flap type, which is made of light aluminum-alloy. The check valves are bolted directly to the pressure bulkhead and supply conditioned air to the system. The valves stop leakage of air from the distribution system in case of failures of the air conditioning system (e.g. duct rupture within the pack).
The pack downstream check valve 15HM (16HM) is a 6 in. (152.3997 mm), pneumatically operated, single spring loaded flap type, which is made of light aluminum-alloy. The check valves are bolted directly to the pressure bulkhead and supply conditioned air to the system. The valves stop leakage of air from the distribution system in case of failures of the air conditioning system (e.g. duct rupture within the pack).
I. Water Injector
The water injector 20HM (21HM) is installed in the ram-air inlet duct, upstream of the heat exchangers. The injector nozzle is connected to the sump of the water extractor with a small diameter pipe. The water from the extractor is delivered under pressure into the ram airflow to increase the cooling capacity through evaporation.
The water injector 20HM (21HM) is installed in the ram-air inlet duct, upstream of the heat exchangers. The injector nozzle is connected to the sump of the water extractor with a small diameter pipe. The water from the extractor is delivered under pressure into the ram airflow to increase the cooling capacity through evaporation.
J. Fan Plenum
The fan plenum 10HM5 (11HM5) is installed between the primary heat exchanger and the ram air outlet. It is made from reinforced plastic. In this plenum the air-cycle machine fan causes a suction in order to get a sufficient cooling airflow on the ground when the ram air is not available.
The fan plenum 10HM5 (11HM5) is installed between the primary heat exchanger and the ram air outlet. It is made from reinforced plastic. In this plenum the air-cycle machine fan causes a suction in order to get a sufficient cooling airflow on the ground when the ram air is not available.
5. Operation/Control and Indicating
Air Cooling System - Component Location ** ON A/C NOT FOR ALL
Air Cooling System - Component Location ** ON A/C NOT FOR ALL
Air Cooling System - Schematic ** ON A/C NOT FOR ALL
Air Cooling System - Schematic ** ON A/C NOT FOR ALL
When the PACK 1 (2) pushbutton switches are pushed, the zone controller 8HK and pack controllers 7HH (27HH) control the flow control valves to supply a constant volumetric flow for all normal operation conditions to the air conditioning packs.
When the PACK 1 (2) pushbutton switches are pushed, the ACSC's 47HH (57HH) control the flow control valves to supply a constant volumetric flow for all normal operation conditions to the air conditioning packs.
Air Cooling System - Component Location ** ON A/C NOT FOR ALL Air Cooling System - Component Location ** ON A/C NOT FOR ALL Air Cooling System - Schematic ** ON A/C NOT FOR ALL Air Cooling System - Schematic ** ON A/C NOT FOR ALL When the PACK 1 (2) pushbutton switches are pushed, the ACSC's 47HH (57HH) control the flow control valves to supply a constant volumetric flow for all normal operation conditions to the air conditioning packs.
A. Normal Operating Mode
When the bleed air enters the system, it is cooled in the primary heat exchanger with ambient ram air. Part of this air passes through the bypass valve 10HH (30HH) (Ref. AMM D/O 21-61-00-00). The remainder is then compressed in the air-cycle machine compressor, which increases the temperature and pressure. It is cooled again in the main heat exchanger with ambient ram air. The air now enters the high-pressure water-extraction loop, where it is cooled to about its dew point.
The high-pressure water-extraction loop has a reheater, a condenser and a water extractor. The reheater uses the turbine inlet air of the air-cycle machine to cool the air in the high-pressure water-extraction loop. The condenser then uses cold turbine air to further cool the air to below its dew point.
The condenser is a heat exchanger, which uses the temperature difference between the turbine outlet air temperature (which is to a sea level dew point of approx. 0 deg.C (32.00 deg.F)) and the reheater outlet temperature air. The condensed water is extracted and drained from the air, as it passes through the high-pressure water extractor.
After the water extractor the air enters the reheater again and the temperature increases to assure that no free water enters the turbine.
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 2 DEG.C (35.60 DEG.F) and 70 DEG.C (158.00 DEG.F). 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.
An anti-ice valve 17HH (37HH) (Ref. AMM D/O 21-61-00-00) 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.
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:
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.
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.
When the bleed air enters the system, it is cooled in the primary heat exchanger with ambient ram air. Part of this air passes through the bypass valve 10HH (30HH) (Ref. AMM D/O 21-61-00-00). The remainder is then compressed in the air-cycle machine compressor, which increases the temperature and pressure. It is cooled again in the main heat exchanger with ambient ram air. The air now enters the high-pressure water-extraction loop, where it is cooled to about its dew point.
The high-pressure water-extraction loop has a reheater, a condenser and a water extractor. The reheater uses the turbine inlet air of the air-cycle machine to cool the air in the high-pressure water-extraction loop. The condenser then uses cold turbine air to further cool the air to below its dew point.
The condenser is a heat exchanger, which uses the temperature difference between the turbine outlet air temperature (which is to a sea level dew point of approx. 0 deg.C (32.00 deg.F)) and the reheater outlet temperature air. The condensed water is extracted and drained from the air, as it passes through the high-pressure water extractor.
After the water extractor the air enters the reheater again and the temperature increases to assure that no free water enters the turbine.
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 2 DEG.C (35.60 DEG.F) and 70 DEG.C (158.00 DEG.F). 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.
An anti-ice valve 17HH (37HH) (Ref. AMM D/O 21-61-00-00) 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.
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.
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.
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.
6. BITE Test
The pack controllers 7HH (27HH) control the BITE function for the air conditioning packs (Ref. AMM D/O 21-61-00-00).
The ACSC's 47HH (57HH) control the BITE function for the air conditioning packs (Ref. AMM D/O 21-61-00-00).
The pack controllers 7HH (27HH) control the BITE function for the air conditioning packs (Ref. AMM D/O 21-61-00-00).
The ACSC's 47HH (57HH) control the BITE function for the air conditioning packs (Ref. AMM D/O 21-61-00-00).