Regenrative Air Cooling System
Regenerative air cooling system is an adjustment of the air cooling system with the expansion of the regenerative heat exchanger. The high-temperature air from the principle compressor is first cooled by the ram air in the heat exchanger. This air is additionally cooled in the regenerative heat exchanger. The cooling turbine cools the segment of air after expansion.
Regenerative Air Cooling System process
1-2 Isentropic ramming of the surrounding air from pressure P1 and temperature T1 to pressure P2 and temperature T2.
1-2′ represents actual ramming of air because of internal friction due to irreversibilities.
2-3′ speaks to isentropic pressure in air in the principle compressor.
2-3′ represents actual compression of air because of internal friction due to irreversibilities.
3′-4 represents cooling of compressed air by ram air in the heat exchanger.
4-5 represents cooling of air in the regenerative heat exchanger.
5-6 represents the isentropic expansion of air in the cooling turbine up to the cabin pressure.
5-6′ represents the actual expansion of air in the cooling turbine.
6′-7 represents heating of air up to the cabin temperature T7.
Q tonnes of refrigeration is the cooling load in the cabin, then the quantity of air required for the refrigeration purpose will be
ma = 210Q/ Cp(T7 – T6′)
m1 = Total mass of air bled from the main compressor, and
m2 = Mass of cold air bled from the cooling turbine for regenerative heat exchanger.
For the energy balance of regenerative heat exchanger, we have
m2Cp ( T8 – T6′) = m1Cp ( T4 – T5)
m2 = m1( T4 – T5)/ ( T8 – T6′)
T8 = Temperature of air leaving to atmosphere from the regenerative heat exchanger
Power required for the refrigeration system,
P = m1Cp ( T3′ – T2′) / 60 kW
C.O.P of the refrigeration system.
= 210Q / m1Cp (T3′ -T2′ )
= 210Q/ P x 60