In a gas turbine generating station the overall compression ratio is 12/1, performed in three stages with pressure ratios of 2.5/1, 2.4/1, and 2/1, respectively. The air inlet temperature to the plant is 25 ?C and intercooling between stages reduce the temperature to 40 ?C. The HP turbine drives the HP and intermediate-pressure compressor stages; the LP turbine drives the LP compressor and the generator. The gases leaving the LP turbine are passed through a heat exchanger which heats the air leaving the HP compressor. The temperature at inlet to the HP turbine is 650 ?C, and reheating between turbine stages raises the temperature to 650 ?C. The gases leave the heat exchanger at a temperature of 200 ?C. The isentropic efficiency of each compressor stage is 0.83, and the isentropic efficiencies of the HP and LP turbines are 0.85 and 0.88, respectively. Take the mechanical efficiency of each shaft as 98 %. The air mass flow is 140 kg/s. Neglecting pressure losses and changes in kinetic energy, and taking the specific heat of water as 4.19 kJ/kg K,

calculate: (i) The power output in kilowatts;

(ii) The cycle efficiency;

(iii) The flow of cooling water required for the intercoolers when the rise in water temperature must not exceed 30 K;

(iv) The heat exchanger thermal ratio.