The cockpit of a jet plane is to be cooled by a simple air refrigeration system. The data available is as follows: Cock-pit cooling load 20 TR Speed of the plane = 1000 km/h Ambient air pressure = 0.35 bar Ambient air temperature = -15°C Ram efficiency = 90% Pressure ratio in the main compressor = 3 Pressure drop in the heat exchanger = 0.1 bar Isentropic efficiencies of main compressor and cooling turbine = 80% Temperature of air entering the cooling turbine = 30°C Pressure of air leaving the cooling turbine = 1.06 bar Pressure in the cock-pit = 1 bar If the cock-pit is to be maintained at 25°C, find : 1. Stagnation temperature and pressure of air entering the main compressor ; 2. Mass flow rate of air to cock-pit ; 3. Power required to drive the refrigerating system; and 4. C.O.P. of system.

The cockpit of a jet plane is to be cooled by a simple air refrigeration system. The data available is as follows: Cock-pit cooling load 20 TR Speed of the plane = 1000 km/h Ambient air pressure = 0.35 bar Ambient air temperature = -15°C Ram efficiency = 90% Pressure ratio in the main compressor = 3 Pressure drop in the heat exchanger = 0.1 bar Isentropic efficiencies of main compressor and cooling turbine = 80% Temperature of air entering the cooling turbine = 30°C Pressure of air leaving the cooling turbine = 1.06 bar Pressure in the cock-pit = 1 bar If the cock-pit is to be maintained at 25°C, find : 1. Stagnation temperature and pressure of air entering the main compressor ; 2. Mass flow rate of air to cock-pit ; 3. Power required to drive the refrigerating system; and 4. C.O.P. of system.