Bootstrap Air Cooling System
Bootstrap Air Cooling System has two heat exchangers rather than one and a cooling turbine drives a secondary compressor rather than a cooling fan. The air seeped from the fundamental compressor is first cooled by the slam air in the main heat exchanger. The cooled air enters the secondary compressor. It is then led to the second heat exchanger where it is again cooled by the ram air. Transport type airplanes use this type of system.
In these videos, I have explained the Working and TS Diagram.
Working Of Bootstrap Air Cooling System
- 1-2 Isentropic ramming of the surrounding air from pressure P1 and temperature T1 to pressure P2 and temperature T2.
- 1-2` Actual ramming process on account of inner erosion because of irreversibilities.
- 2′- 3 Isentropic compression of air in the primary compressor.
- 2-3′ Actual compression of air as a result of inward erosion because of irreversibilities.
- 3′- 4 Cooling of the air in the primary heat exchanger. During this process, the drop in pressure is neglected.
- 4-5 Isentropic compression of cooled air, from the main heat exchanger, in the auxiliary compressor.
- 4-5′ Actual Compression process in light of interior erosion because of irreversibilities.
- 5′- 6 Cooling by ram air in the secondary heat exchanger. During this process, the drop in pressure is neglected.
- 6-7 Isentropic expansion of cooled air in the cooling turbine up to compartment pressurization.
- 6-7′ Actual Expansion of the cooled air in the cooling turbine.
- 7′- 8 Heating of air up to the compartment temperature T8.
Q tonnes of refrigeration is the cooling load in the compartment, at that point, the amount of air required for the refrigeration will be
ma = 210 Q / Cp ( T8 – T7`)
Power required during refrigeration system
P = maCp ( T3` – T2` ) / 60
Unit – kW
C.O.P during the refrigeration system
C.O.P = 210 / P x 60