A boot strap cooling system of 20 tonnes is used in an airplane. The temperature and pressure conditions of atmosphere are 15°C and 0.9 bar. The pressure of air is increased from 0.9 bar to 1.2 bar due to ramming. The pressures of air leaving the main and auxiliary compressor are 3 bar and 4 bar respectively. The 50% of the total heat of air leaving the main compressor is removed in the first heat exchanger and 30% of their total heat of air leaving the auxiliary compressor is removed in the second heat exchanger. The cabin pressure is 1.02 bar and temperature of air leaving the cabin should be greater than 25°C. Assume ramming action, compression and expansion are isentropic. Take CP=1 kJ/kg.K and γ=1.4. Find: (A) Power required to take cabin load. (B) COP of the system.
A boot strap cooling system of 20 tonnes is used in an airplane. The temperature and pressure conditions of atmosphere are 15°C and 0.9 bar. The pressure of air is increased from 0.9 bar to 1.2 bar due to ramming. The pressures of air leaving the main and auxiliary compressor are 3 bar and 4 bar respectively. The 50% of the total heat of air leaving the main compressor is removed in the first heat exchanger and 30% of their total heat of air leaving the auxiliary compressor is removed in the second heat exchanger. The cabin pressure is 1.02 bar and temperature of air leaving the cabin should be greater than 25°C. Assume ramming action, compression and expansion are isentropic. Take CP=1 kJ/kg.K and γ=1.4.
Find:
(A) Power required to take cabin load.
(B) COP of the system.
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