How will the answers of Prob. 11-77 change when the isentropic efficiency of each compressor is 85 percent and the isentropic efficiency of the turbine is 95 percent?
Prob. 11-77
An ideal gas refrigeration system with two stages of compression with intercooling as shown in Fig. P11-77 operates with air entering the first compressor at 90 kPa and - 24oC. Each compression stage has a pressure ratio of 3 and the two intercoolers can cool the air to 5oC. Calculate the coefficient of performance of this system and the rate at which air must be circulated through this system to service a 45,000 kJ/h cooling load. Use constant specific heats at room temperature.

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QH.1 ,I OH2 Compressor Compressor Turbine