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May 30/02
Revision 7
• Water Separator Anti-Ice System
• Cooling Fan
• Cooling Air Distribution
(1) Primary Heat Exchanger:
The primary heat exchanger is the first stage of the refrigeration
process. Ram air from the dorsal fin inlet is used as a coolant. The
heat exchanger is a “single pass” type exchanger and is located in
the tail compartment.
Air exiting the heat exchanger is split into two ducts. One duct routes
air into the eye of the compressor section of the ACM. The other
duct routes air through the water separator anti-ice valve into the
anti-ice muff assembly, bypassing the ACM and secondary heat
exchanger.
(2) Air Cycle Machine (ACM) and ACM Overtemperature Thermal
Switch:
The ACM is an expansion turbine which reduces air temperature by
causing the air to perform useful work, resulting in lower air pressure
and thus, lower air temperature. The work extracted from the
airstream in the turbine section is absorbed a compressor wheel
directly shafted to the turbine wheel and located in a separate
chamber on the upstream side of the unit. A large percentage of the
work extracted from the airstream by the turbine wheel is used by
the compressor wheel. As the compressor wheel is performing work
on the upstream air, its pressure and temperature are increased.
This work arrangement is called a pressure recovery system or
“bootstrap” system.
With the ACM in full operation (no airflow to the anti-ice valve),
airflow moves through the compressor section to the secondary
heat exchanger, then to the turbine section nozzle, exiting out the
eye of the turbine section into the mixing muff.
A 450° F thermal switch is incorporated into the discharge side of
the bootstrap compressor to monitor discharge air temperature. If a
malfunction causes low or no airflow across the heat exchangers,
the compressor discharge temperature will rise accordingly. At 450°
F, the switch causes an amber L-R COOL TURB HOT message to
be displayed on CAS. Additionally, when on the ground, the ECS
pack will be automatically shut off due to a protection circuit passing
through the ground configuration of the nutcracker system.
An amber L-R COOL TURB HOT CAS message in flight may be the
result of either an excessive air supply to the ACM, resulting in an
overspeed/overtemperature condition, or an air bearing failure in the
ACM. Excessive airflow from 12th stage compensation can be the
result of operating cowl anti-ice and/or wing anti-ice at high altitudes.
(3) Secondary Heat Exchangers:
Secondary heat exchangers are installed adjacent to the primary
heat exchangers. Ram air from the dorsal fin inlet is used as a
coolant.
(4) Water Separator System:
OPERATING MANUAL
2A-21-00 PRODUCTION AIRCRAFT SYSTEMS
Page 24
May 30/02
Revision 7
Air expansion inside the cooling turbine and resultant discharge
temperatures below ambient forces moisture into the air where it
condenses. A two-section water separator provides a means for
removing the water.
The first section consists of a coalescer which transforms the many
small droplets into a few large drops by forcing the water through a
coarse mesh cloth bag. In the second section, the airstream is
forced to swirl by means of a series of vanes so that the large drops
are spun to the outside walls. Water extracted from the air is also
sprayed into the secondary heat exchanger cooling air inlet to assist
in cooling.
The water separator is capable of removing approximately 80% of
all liquid state water passing through it but it cannot, however,
remove water vapor. The water separator also contains a relief valve
which, if the coalescer becomes clogged, bypasses the air through
the unit. In this case, dehumidification would not take place.
(5) Water Separator Anti-Ice System:
During cool, moist conditions, cooling turbine discharge
temperatures can fall low enough that condensed water freezes. To
prevent the coalescer from becoming clogged with ice crystals and
restricting airflow, a water separator anti-ice system is installed in
the tail compartment. The system consists of a water separator antiice
valve, a sensor and a bypass duct mixing muff assembly.
The water separator anti-ice valve is a butterfly-type shutoff and
modulating valve. It controls the refrigeration unit cold air outlet
temperature to a minimum of 37° F (nominal) by modulating the flow
of compressor inlet air to the anti-ice muff at the turbine discharge.
Valve position is controlled by a torque motor in response to signals
received from the water separator anti-ice sensor/controller.
　
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本文鏈接地址：灣流4操作手冊 Gulfstream IV Operating Manual 1(45)