Carnot engine

Definition

A Carnot engine is an idealized heat engine that operates on the reversible Carnot cycle. It represents the maximum possible efficiency that any heat engine can achieve, as dictated by the second law of thermodynamics.

5 Must Know Facts For Your Next Test

1. The Carnot engine's efficiency depends only on the temperatures of the hot and cold reservoirs.
2. Carnot engines are theoretical constructs; no real engine can achieve the perfect efficiency of a Carnot cycle.
3. The efficiency equation for a Carnot engine is $1 - \frac{T_C}{T_H}$, where $T_C$ and $T_H$ are the absolute temperatures of the cold and hot reservoirs, respectively.
4. A Carnot cycle consists of four reversible processes: two isothermal (constant temperature) processes and two adiabatic (no heat transfer) processes.
5. The second law of thermodynamics states that no engine can be more efficient than a Carnot engine operating between the same two temperatures.

Review Questions

• What determines the efficiency of a Carnot engine?
• Why can't any real engine achieve the same efficiency as a Carnot engine?
• What are the four processes that make up a Carnot cycle?

Related terms

Second Law of Thermodynamics: A principle stating that total entropy always increases in an isolated system; it also implies that no heat engine can be perfectly efficient.

Isothermal Process: A thermodynamic process occurring at constant temperature.

Adiabatic Process: A process in which no heat is transferred to or from the system by its surroundings.