Carnot cycle

Definition

The Carnot cycle is an idealized thermodynamic cycle that provides the maximum possible efficiency for a heat engine. It consists of two isothermal processes and two adiabatic processes.

5 Must Know Facts For Your Next Test

1. The Carnot cycle involves four stages: isothermal expansion, adiabatic expansion, isothermal compression, and adiabatic compression.
2. The efficiency of a Carnot engine depends only on the temperatures of the hot and cold reservoirs, given by $\eta = 1 - \frac{T_C}{T_H}$.
3. No real engine can be more efficient than a Carnot engine operating between the same two temperatures.
4. During the isothermal processes, the system absorbs or releases heat without changing temperature.
5. In adiabatic processes within the Carnot cycle, there is no heat exchange with the surroundings.

Review Questions

• What are the four stages of the Carnot cycle?
• How is the efficiency of a Carnot engine calculated?
• Why can't any real engine surpass the efficiency of a Carnot engine?

Related terms

Isothermal Process: A thermodynamic process in which temperature remains constant while the system exchanges heat with its surroundings.

Adiabatic Process: A thermodynamic process where no heat is transferred to or from the system; temperature changes occur due to work done on or by the system.

Second Law of Thermodynamics: A principle stating that natural processes increase entropy over time, implying that energy transfers are not completely efficient.