In a gas turbine generating set two stages of compression are used with an intercooler between stages. The HP turbine drives the HP compressor, and the LP turbine drives the LP compressor and the generator. The exhaust from the LP turbine through a heat exchanger which transfer heat to the air leaving the HP compressor. There is a reheat combustion chamber between turbine stages which raises the gas temperature to 8000C, which is also the gas temperature at entry to the HP turbine. The overall pressure ratio is 30, each compressor having the same pressure ratio, and the air temperature at entry to the unit is 300C. The heat exchanger thermal ratio may be taken as 0.75, and intercooling is complete between compressor stages. Assume isentropic efficiencies of 0.85 for both compressor stages, and 0.9 for both turbine stages, and the 4% of the work of each turbine is used in overcoming friction. Neglecting the losses in pressure, and assuming that velocity changes are negligibly small, calculate: 1) the power output in kilowatts for mass flow of 150 kg/s; 2) the overall cycle efficiency of the plant.
In a gas turbine generating set two stages of compression are used with an intercooler between stages. The HP turbine drives the HP compressor, and the LP turbine drives the LP compressor and the generator. The exhaust from the LP turbine through a heat exchanger which transfer heat to the air leaving the HP compressor. There is a reheat combustion chamber between turbine stages which raises the gas temperature to 8000C, which is also the gas temperature at entry to the HP turbine. The overall pressure ratio is 30, each compressor having the same pressure ratio, and the air temperature at entry to the unit is 300C. The heat exchanger thermal ratio may be taken as 0.75, and intercooling is complete between compressor stages. Assume isentropic efficiencies of 0.85 for both compressor stages, and 0.9 for both turbine stages, and the 4% of the work of each turbine is used in overcoming friction. Neglecting the losses in pressure, and assuming that velocity changes are negligibly small, calculate:
1) the power output in kilowatts for mass flow of 150 kg/s;
2) the overall cycle efficiency of the plant.
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