What is the name of the cycle used in steam power plants?

The cycle used in steam power plants is the Rankine cycle. It is an idealized thermodynamic model for converting heat into mechanical work using a working fluid, most commonly water and steam.

A basic Rankine cycle has four stages. A pump raises the pressure of liquid water; a boiler adds heat and turns it into high-pressure steam; the steam expands through a turbine and produces work; and a condenser removes heat, turning the exhaust back into liquid water. The fluid then returns to the pump, completing the loop.

The cycle is named after Scottish engineer and physicist William John Macquorn Rankine, who developed important contributions to thermodynamics in the 19th century. Unlike the Carnot cycle, the Rankine cycle is practical for phase-changing fluids because it compresses liquid rather than vapor, greatly reducing the pump work required.

Real plants include friction, pressure losses, and non-isentropic turbine and pump operation. Superheating, reheating, and regenerative feedwater heating improve efficiency and help prevent damaging moisture in turbine exhaust.