Refrigerator

Definition

A refrigerator is a device that transfers heat from a low-temperature region to a high-temperature region using work, typically powered by electricity. It operates based on the principles of thermodynamics and is used to keep food and other items cool.

5 Must Know Facts For Your Next Test

1. Refrigerators operate according to the Second Law of Thermodynamics, which states that heat naturally flows from hot to cold regions, but can be forced to flow from cold to hot regions with the input of work.
2. The Coefficient of Performance (COP) is a key measure of a refrigerator's efficiency, defined as the ratio of heat removed from the cold reservoir to work input: $COP = \frac{Q_c}{W}$.
3. In an ideal refrigerator cycle, the working fluid undergoes four main processes: isentropic compression, isobaric heat rejection, isenthalpic expansion, and isobaric heat absorption.
4. The electrical power consumed by a refrigerator can be calculated using Ohm's law and Kirchhoff's rules if resistors in series and parallel are involved in its circuitry.
5. Heat pumps and refrigerators are similar in design but differ in purpose; heat pumps transfer thermal energy into a space for heating purposes.

Review Questions

• What principle does a refrigerator primarily rely on according to thermodynamics?
• How do you calculate the Coefficient of Performance (COP) for a refrigerator?
• List and describe the four main processes that occur during an ideal refrigeration cycle.

Related terms

Second Law of Thermodynamics: A fundamental principle stating that entropy within an isolated system always increases over time and that heat cannot spontaneously flow from colder bodies to hotter bodies without external work.

Coefficient of Performance (COP): A measure of efficiency for refrigerators and heat pumps, calculated as the ratio of heat removed or added to the work input: $COP = \frac{Q_c}{W}$ for refrigerators.

Resistors in Series: An electrical circuit configuration where resistors are connected end-to-end so that current flows through each resistor sequentially; total resistance is the sum of individual resistances.