Air standard Brayton cycle: description of the processes, p-v diagram. Air standard Brayton cycle: description of the processes, p-v diagram.
The Correct Answer and Explanation is :
The Air Standard Brayton Cycle is a thermodynamic cycle that represents the idealized operation of a gas turbine engine, typically used in aircraft engines, power plants, and other machinery where compressed air is heated, expanded, and cooled. It is a simplified version of the real Brayton cycle, assuming constant specific heats and no friction, heat losses, or other losses.
Description of Processes in the Air Standard Brayton Cycle:
- Process 1-2 (Isentropic Compression):
The air enters the compressor at low pressure and temperature and is compressed adiabatically (no heat exchange with the surroundings). The pressure increases as the volume decreases, and the temperature rises in the process. - Process 2-3 (Isochoric Heat Addition):
The compressed air enters the combustion chamber (or a heat exchanger in the air-standard assumption) where it is heated at constant pressure. This process results in a temperature increase and a corresponding increase in the internal energy of the air. - Process 3-4 (Isentropic Expansion):
The high-pressure, high-temperature air expands through the turbine, doing work to drive the compressor and other components. The process is adiabatic, and the temperature and pressure decrease as the volume increases. - Process 4-1 (Isochoric Heat Rejection):
The air exits the turbine at low pressure and temperature and is cooled in a heat exchanger, returning to its initial state to complete the cycle.
p-v Diagram:
The p-v diagram for the Brayton cycle shows the changes in pressure (p) versus volume (v) for each of these four processes. It starts at point 1 with low pressure and volume, rises to point 2 during compression, moves horizontally to point 3 with a constant pressure and increased temperature, then drops to point 4 during expansion, and finally moves back to point 1, completing the cycle.
Let me generate the p-v diagram for you.
The p-v diagram for the Air Standard Brayton Cycle is shown above, illustrating the four key processes:
- Process 1-2 (Isentropic Compression): The volume decreases while pressure increases as the air is compressed adiabatically in the compressor.
- Process 2-3 (Heat Addition): The air is heated at constant pressure, causing an increase in both temperature and volume.
- Process 3-4 (Isentropic Expansion): The air expands in the turbine, where the pressure drops and the volume increases.
- Process 4-1 (Heat Rejection): The air is cooled at constant pressure, returning to its original state.
This cycle is idealized and doesn’t account for real-world inefficiencies, but it serves as a useful model for understanding how gas turbines work.
