A thermodynamic cycle is a series of thermodynamic processes that takes a system through different states and eventually returns it to its original state. Despite ending where it began, the system typically transfers energy—as work or heat—to or from its surroundings.
Key features:
- In a full cycle, the system’s internal energy remains unchanged, since it returns to its starting state.
- The net work done by the system over one cycle equals the net heat added to the system (by the First Law of Thermodynamics).
Examples of thermodynamic cycles:
- Carnot cycle: An idealized, reversible cycle with maximum efficiency.
- Otto cycle: The basic cycle for gasoline engines.
- Rankine cycle: Used in steam power plants.
- Brayton cycle: Found in jet engines and gas turbines.
Thermodynamic cycles are fundamental to heat engines, refrigerators, and power plants, where controlled energy transformation is essential.