Which statement about the Brayton cycle correctly characterizes its name?

• A. It is known as the constant pressure cycle.
• B. It is known as the constant temperature cycle.
• C. It is known as the constant volume cycle.
• D. It is known as the constant mass cycle.

Answer: (A)

The key idea is that the Brayton cycle heats the working fluid at almost constant pressure. In a gas turbine, air is compressed to a high pressure, then burned in the combustor while the pressure is held near that same high value as fuel raises the temperature. The heat-addition step is essentially isobaric, and the subsequent exhaust and heat rejection also occur at roughly the same pressure level as the compressor discharge. Because the defining heat transfer happens at a nearly constant pressure, the cycle earns the name constant-pressure cycle. This differs from cycles where heat is added at a fixed volume or at a fixed temperature, which would describe different engine cycles.