Renewable energies-LEC7

Brayton Cycle( Joule s cycle):
The Ideal Cycle for Gas Turbine Engines
• In reality, gas turbines operate on an open cycle
• Fresh air is continuously drawn into the compressor and exhaust gases are thrown out
• The open gas-turbine cycle can be modeled as a closed cycle
• The combustion process is replaced by a constant-pressure heat-addition process and the exhaust process is replaced by a constant-pressure heat-rejection process

• In reality, gas turbines operate on an open cycle
• Fresh air is continuously drawn into the compressor and exhaust gases are thrown out
• The open gas-turbine cycle can be modeled as a closed cycle
• The combustion process is replaced by a constant-pressure heat-addition process and the exhaust process is replaced by a constant-pressure heat-rejection process

Thermodynamic Analysis
• The four processes of the Brayton cycle are executed in steady-flow devices
• When changes in kinetic and potential energies are neglected, the energy balance for one of the processes can be
expressed

Thermal Efficiency
The thermal efficiency of the ideal Brayton cycle under the cold-air-
standard assumptions becomes