mediate-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 the 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
The overall compression ratio in a gas turbine engine is 12/1 which is 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 reduces 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
the 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
shaft as 98%. The air mass flow is 346 kg/s. Neglecting pressure losses and changes in kinetic
energy, and taking the specific heat of the water as 4.19 kJ/kg K. For the compression process
take cp = 1.005 kJ/kg K and γ = 1.4; for the combustion process, and for the expansion process
take cp = 1.15 kJ/kg K and γ = 1.333. Neglect the mass of fuel.
(i) Compute the power output in kilowatts;
(ii) Calculate the cycle efficiency;
(iii) Calculate the flow of cooling water required for the intercoolers when the rise in
water temperature must not exceed 30 K;
iv) Calculate the heat exchanger thermal ratio.
Note: Numerical answers till the 3rd decimal are required to be written.
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