It is used in aircrafts of the entire world. There are different cooling arrangements for the air conditioning of aircrafts. Here boot strap and reduced ambient cooling systems are discussed here.
BOOT STRAP AND REDUCED AMBIENT AIRCRAFT COOLING SYSTEMS
Boot Strap Air Refrigeration System: Two systems
- Without evaporative cooling,
- With evaporative cooling
FIG. BOOT STRAP SYSTEM ON TEMPERATURE ENTROPY CHART
In this, there are two compressors, two heat exchangers and one turbine. Normally second compressor is run by the expansion turbine. In case of evaporative cooling in Boot strap, another water cooled heat exchanger is placed after the second heat exchanger in Fig. above.
Reduced Ambient Air Refrigeration System
Fig. REDUCED AMBIENT AIRCRAFT COOLING SYSTEM ON TEMP ENTROPY CHART
It uses two turbines and one compressor. Turbine 1 uses rammed air. The air from turbine 1 enters the heat exchanger. Turbine 2 uses air after the heat ex-changer for further cooling.
Turbine 1 has input and output points as 2 and 4.
Cooled air from turbine 1 enters the first Heat exchanger at point 4.
Heat exchanger has input at points 3 and 5.
CAUTION: RAMMED AIR IS NOT USED IN THE HEAT EXCHANGER BECAUSE RAMMED AIR IS FED TO TURBINE 1.
Turbine 2 has input and output points as 5 and 6.
Procedure of calculation is similar to the BOOT STRAP SYSTEM.