-an air-cycle machine,
 -
a high-pressure water extractor,

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a reheater,

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a condenser,

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a primary heat exchanger,

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a main heat exchanger,

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a fan plenum,

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for various other components of the pack refer to chapter 21-61-00. A water injector 20HM (21HM) and a downstream check valve 15HM (16HM) are installed at each pack.

 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.

 Air Cooling System - Schematic
 Figure 002

R 1EFF : 001-003, 051-054, 1 21-52-00Page 5 1 1 May 01/05 1 1 1CES 1

 Air Cooling System - Schematic
 Figure 002A

R 1EFF : 004-049, 055-099, 101-149, 151-199, 1 21-52-00Page 6 1201-299, 301-399, 401-499, 1Aug 01/05 1 1 1CES 1

 Pressure/Temperature Diagram Figure 003
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R **ON A/C 001-049, 051-099, 101-149, 151-199, 201-299, 301-399,
 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).

R **ON A/C 401-499,
 B. Air-Cycle Machines 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.
 **ON A/C ALL
 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.
 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.

 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.
 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).
 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.
 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.
R
 4. Component Description
_____________________

R **ON A/C 001-049, 051-099, 101-149, 151-199, 201-299,
 A. Air Conditioning Packs (Ref. Fig. 004) 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.
　
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