. In a gas turbine plant, air enters a compressor at atmosphericconditions of 15 ?C, 1.0133 bar and is compressed through apressure ratio of 10. The air leaving the compressor passes througha heat exchanger before entering the combustion chamber. The hotgases leave the combustion chamber at 800 ?C and expand through anHP turbine which drives the compressor. On leaving the HP turbinethe gases pass through a reheat combustion chamber which raises thetemperature of the gases to 800 ?C before they expand through thepower turbine, and hence to the heat exchanger where they flow incounter-flow to the air leaving the compressor. Using the databelow, neglecting the mass flow rate of fuel and changes ofvelocity throughout,

calculate: (i) The airflow rate required for a net power outputof 10 MW;

(ii) The work ratio of the cycle;

(iii) The temperature of the air entering the first combustionchamber;

(iv) The overall cycle efficiency.

Data: Isentropic efficiency of compressor, 80 %; isentropicefficiencies of HP and power turbine, 87 and 85 %; mechanicalefficiency of HP turbine-compressor drive, 92 %; mechanicalefficiency of power turbine drive, 94 %; thermal ratio of heatexchanger, 0.75; pressure drop on air side of heat exchanger, 0.125bar; pressure drop in first combustion chamber, 0.100 bar; pressuredrop in reheat combustion chamber, 0.080 bar; pressure drop on gasside of heat exchanger, 0.100 bar.

ANSWERS(91.0 kg/s; 0.25; 611 ?C; 18.9 %)