A closed cycle gas turbine: which statement is true?

• A. Does not need a combustion chamber
• B. Is the most common type of gas turbine
• C. Recycles the same working fluid
• D. Burns fuel with spent exhaust gas.

Answer: (C)

In a closed-cycle gas turbine, the working fluid is kept in a sealed loop and continuously recirculated. Fuel is burned to add heat, but the gas itself isn’t exhausted and replaced; it stays in the loop, being compressed, heated, expanded through the turbine, and then cooled and returned to the compressor. That recirculation of the same working fluid is why the correct statement is that the system recycles the same working fluid.

The other ideas don’t fit because energy must still be added to the loop via a combustion chamber or external heater, so it isn’t true that the cycle doesn’t need a combustion chamber. In practice, open-cycle gas turbines, where the working fluid is exhausted to the atmosphere and fresh air is drawn in, are far more common. And you don’t burn fuel with spent exhaust gas inside the closed loop—the exhaust is separated and treated rather than used as the oxidizer within the same cycle.