Boot strap air cooling system
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The document presents information on a bootstrap air cooling system suitable for aircraft. It consists of two heat exchangers, a secondary compressor driven by a turbine, and uses ram air and compression to cool and circulate air. Ambient air is compressed by the main aircraft compressor then cooled in an air cooler before further compression and cooling. It is then expanded through a turbine to provide cooled air to the aircraft cabin. Advantages are that air is readily available, non-toxic, and pressures are low. A limitation is that it requires aircraft flight for ram air cooling and is not suitable for ground use without an additional fan.
Boot strap air cooling system
- 1. PRESENTATION ON “BOOT-STRAP AIR COOLING SYSTEM” REFRIGERATION AND AIR CONDITIONING SUBMITTED BY: HIMANSHI GUPTA (140120119057)/ ME/A2 GUIDED BY: PROF. NIMESH GAJJAR (2161908) GANDHINAGAR INSTITUTE OF TECHNOLOGY
- 2. BOOT-STRAPAIR COOLING SYSTEM 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 The main components of this system are: • Two heat exchangers (air cooler and after cooler) • A secondary compressor, which is driven by the turbine of the cooling system APPLICATION: This system is suitable for high speed aircraft, where in the velocity of the aircraft provides the necessary airflow for the heat exchangers
- 3. WORKING • The air bled from the main compressor is first cooled by the ram air in the first 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 cooling turbine
- 5. • 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 T-s diagram for a boot-strap air cooling system
- 6. • If Q tonnes of refrigeration is the cooling load in the cabin, then the quantity of air required for the refrigeration purpose will be • Power required for the refrigeration system, • C.O.P. of the refrigerating system,
- 7. ADVANTAGES • The air is easily available and there is no cost of the refrigerant • The air is non-toxic and non-inflammable • The leakage of air in small amounts is tolerable • The air is light in weight per tonne of refrigeration • The chilled air is directly used for cooling, there by eliminating the cost of separate evaporator • The pressure in the whole system is quite low, therefore the piping, ducting etc. are quite simple to design, fabricate and maintain
- 8. LIMITATIONS • 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 • Since the system does not consist of a separate fan for driving the air through the heat exchangers, it is not suitable for ground cooling
- 9. Thank You