A gas-turbine power plant operates on the regenerative Brayton cycle between the pressure limits of 100 and 700 kPa. Air enters the compressor at 308C at a rate of 12.6 kg/s and leaves at 2608C. It is then heated in a regenerator to 4008C by the hot combustion gases leaving the turbine. A diesel fuel with a heating value of 42,000 kJ/kg is burned in the combustion chamber with a combustion efficiency of 97 percent.
The combustion gases leave the combustion chamber at 8718C and enter the turbine whose isentropic efficiency is 85 percent. Treating combustion gases as air and using constant specific heats at 5008C, determine (a) the isentropic efficiency of the compressor, (b) the effectiveness of the regenerator, (c) the air-fuel ratio in the combustion chamber, (d) the net power output and the back work ratio, (e) the thermal efficiency, and (f) the second-law efficiency of the plant. Also determine (g) the second-law efficiencies of the compressor, the turbine, and the regenerator, and (h) the rate of the energy flow with the combustion gases at the regenerator exit. (a) 0.881, (b) 0.632, (c) 78.1, (d) 2267 kW, 0.583, (e) 0.345, (f) 0.469, (g) 0.929, 0.932, 0.890, (h) 1351 kW

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Regenerator Combustion chamber 100 kPa 30 C 400°C 871C3 700 kPa 260 C Compressor Turbine FIGURE P9-148