Carnot engine

Definition

A Carnot engine is a theoretical thermodynamic cycle proposed by Nicolas Léonard Sadi Carnot. It operates between two heat reservoirs and provides the maximum possible efficiency for converting heat into work.

5 Must Know Facts For Your Next Test

1. The Carnot engine operates on a reversible cycle consisting of two isothermal processes and two adiabatic processes.
2. The efficiency of a Carnot engine depends only on the temperatures of the hot and cold reservoirs: $\eta = 1 - \frac{T_C}{T_H}$, where $T_C$ and $T_H$ are the absolute temperatures of the cold and hot reservoirs, respectively.
3. No real engine can be more efficient than a Carnot engine operating between the same two temperatures.
4. The work done by the Carnot engine in one complete cycle is equal to the net heat absorbed by the system.
5. The Carnot cycle serves as an idealized model that helps set an upper limit on the efficiency of all real heat engines.

Review Questions

• What are the four processes that make up a Carnot cycle?
• How is the efficiency of a Carnot engine calculated?
• Why can't any real engine be more efficient than a Carnot engine?

Related terms

Second Law of Thermodynamics: States that heat cannot spontaneously flow from a colder body to a hotter body and that entropy, or disorder, tends to increase over time in an isolated system.

Isothermal Process: A process in which temperature remains constant while heat is exchanged between the system and its surroundings.

Adiabatic Process: A process in which no heat is exchanged with the surroundings; all changes in internal energy result from work done on or by the system.