During operation, hot gases expand in which part of the microturbine system?

In a microturbine system, hot gases expand primarily in the gas turbine. This is a critical stage in the energy conversion process. After the fuel is combusted, it produces high-temperature and high-pressure gases. These gases then enter the gas turbine, where they expand rapidly. This expansion is what drives the turbine's rotor, converting the thermal energy of the hot gases into mechanical energy.

The mechanical energy generated in the gas turbine is subsequently used to drive a generator, which converts it into electrical energy. During this expansion process, the temperature and pressure of the gases decrease, and it’s this drop in pressure that allows for the effective conversion of energy.

While the compressor compresses the incoming air before it enters the combustion chamber and the boiler is involved in scenarios with water and steam, neither of these components is responsible for the expansion of hot gases. The gas turbine is specifically designed for that purpose, making it the correct answer in this context.