A power-generating Brayton cycle is shown in the figure below. The system is operating in a mountainous region where the ambient temperature and pressure are 250 K and 85 kPa, respectively. The mass flow rate of air through the system is 200 kg/s. The system uses two compressors with pressure ratios of 6 and 4, respectively. The isentropic efficiency of each compressor is 90%. The air is cooled to 300 K in the heat exchanger between the compressors. The temperature at the combustor exit is 1500 K. The isentropic efficiency of the turbine is 75%. The system also includes a regenerative heat exchanger with an effectiveness of 80%. (a) Calculate the net power output, in kW, and the thermal efficiency, in %. (b) Draw the T-s diagram for the cycle and label the states.

 

8 Tregen = 0.80 + Regen HEX 5 Combustor Nc1 = 0.90 P/P,=6 Nc2 = 0.90 Palp3=4 6 %3! T= 1500 K 7 Compressor 1 Compressor 2 Turbine m = 0.75 - 3 T,=250 K P;=85 kPa m,=200 kg/s Intercooler T3= 300 K