Vesihöyrymuunnoksessa

Vesihöyrymuunnoksessa, or the Rankine cycle, is a thermodynamic cycle that converts heat into work. It is the most common cycle used in steam-powered heat engines, such as steam turbines and reciprocating steam engines. The cycle consists of four processes: isentropic compression, isobaric heat addition, isentropic expansion, and isobaric heat rejection.

In the isentropic compression process, a working fluid, typically water, is compressed from a low-pressure state to a high-pressure state without any heat exchange. This process increases the temperature and pressure of the fluid.

Next, in the isobaric heat addition process, heat is added to the fluid at constant pressure. This causes the fluid to expand and convert into steam, increasing its volume and temperature.

The isentropic expansion process follows, where the high-pressure, high-temperature steam expands through a turbine, converting the thermal energy into mechanical work. This process is isentropic, meaning it occurs without any heat exchange.

Finally, in the isobaric heat rejection process, the low-pressure, low-temperature steam is cooled and condensed back into water at constant pressure. This process rejects the heat that was added during the isobaric heat addition process.

The Rankine cycle is widely used in power plants, where it is employed to generate electricity. The efficiency of the Rankine cycle can be improved by increasing the temperature and pressure of the steam, using more efficient turbines, or by employing reheating and regenerative processes. However, the cycle is limited by the Carnot efficiency, which is determined by the temperature difference between the heat source and the heat sink.