The document discusses the bootstrap air cycle refrigeration system. It consists of a primary heat exchanger, secondary heat exchanger, and cooling turbine. Ram air is used to cool the heat exchangers. High pressure air is compressed, cooled in the primary heat exchanger, compressed further, and has more heat removed in the secondary heat exchanger before expanding through the turbine to provide cabin cooling. The bootstrap system uses two compressors to raise the air pressure in two stages for use on aircraft to provide cooling while in flight when ram air is available to aid heat removal.

1. BootstrapAir Cycle
RefrigerationSystem
By: Siddharth Bhatnagar
B2 | 147
PresentedTo: Mr. Ashish Nayyar

2. The term Bootstrap as used in Air Cycle
Refrigeration indicates a system in which the
pressure of the working fluid is raised in two
levels by using two compressors, before the
working fluid which is air, expands in the turbine
section.
Consists of a Primary Heat Exchanger, a
Secondary Heat Exchanger and a Cooling
Turbine.
Ram Air is used as a sink in the Primary and
Secondary Heat Exchangers.
Bootstrap Air Cycle
Refrigeration
System.
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3. The Bootstrap refrigeration system is mostly used
in Transport Aircrafts. The Basic System will cool
the Cabin when the Airplane is on the Ground.
The Bootstrap system requires the Airplane to
be in flight so that the Ram Air can cool the Heat
Exchangers.
High Pressure air is first cooled in the Primary
Heat Exchanger. The air is then compressed to a
Higher Pressure and Temperature in the
compressor of the Cooling Turbine. A substantial
amount of heat of compression is removed in
the secondary heat exchanger and the air is
cooled further as it expands through the Turbine
section of the CoolingTurbine.
Bootstrap Air Cycle
Refrigeration
System.
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4. Bootstrap Air Cycle
Refrigeration
System.
Fig.1: Bootstrap Air Cycle Refrigeration System.
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5. Bootstrap Air Cycle
Refrigeration
System.
Ambient Air state 1 is pressurized to state 2 due
to the Ram Effect.
This air is further compressed to state 3 in the
main compressor.
The air is then cooled to state 4 in the air cooler.
The heat rejected in the air cooler is absorbed by
the ram air at state 2.
The air from the air cooler is further compressed
from state 4 to state 5 in the secondary
compressor.
It is then cooled to state 6 in the after cooler,
expanded to cabin pressure in the cooling turbine
and is supplied to the cabin at a low temperature
T7.
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6. Bootstrap Air Cycle
Refrigeration
System.Fig.2: Bootstrap CycleTemperature- Pressure Diagram.
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7. References.
 Refrigeration and Air Conditioning Lecture
Version I, IIT Kharagpur.
Wikipedia.
 Google.
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8. Questions areWelcomed
THANKYOU!