Perfect refrigerator

Definition

A perfect refrigerator is a hypothetical device that transfers heat from a cold reservoir to a hot reservoir without any input of work, violating the Second Law of Thermodynamics. Such a device is impossible in practice because it contradicts fundamental thermodynamic principles.

5 Must Know Facts For Your Next Test

1. A perfect refrigerator would violate the Kelvin-Planck statement of the Second Law of Thermodynamics.
2. The concept of a perfect refrigerator is used to illustrate the impossibility of achieving 100% efficiency in heat transfer processes.
3. Real refrigerators require work input to transfer heat from a colder area to a warmer one, unlike the perfect refrigerator.
4. The coefficient of performance (COP) for an actual refrigerator is always less than infinity, whereas for a perfect refrigerator it would be infinite.
5. Understanding why a perfect refrigerator cannot exist helps reinforce the concept of entropy and its implications in thermodynamic systems.

Review Questions

• Why does the existence of a perfect refrigerator violate the Second Law of Thermodynamics?
• How does the coefficient of performance (COP) differ between real refrigerators and a hypothetical perfect refrigerator?
• What fundamental principle does the concept of a perfect refrigerator help illustrate?

Related terms

Second Law of Thermodynamics: A law stating that total entropy can never decrease over time for an isolated system and that processes involving energy transfers are irreversible.

Kelvin-Planck Statement: A form of the Second Law of Thermodynamics stating it is impossible to construct an engine that operates on a cycle and produces no effect other than converting all heat into work.

Coefficient Of Performance (COP): $$\text{COP} = \frac{Q_c}{W}$$ where $$Q_c$$ is the amount of heat removed from the cold reservoir, and $$W$$ is the work input; it measures efficiency for refrigeration cycles.