Refrigerators use the mechanism of removing heat from substances under controlled conditions based on the second law of thermodynamics. The first commercial refrigerator was invented in 1854 and home refrigerators became popular in the 1930s after the introduction of Freon. Refrigerators work by passing a colder liquid around an object to take out heat using key components like a compressor, condenser, evaporator, and throttling device to circulate refrigerant and maintain different temperature zones for food storage.

1. REFRIGERATOR
 Refrigerator is a machine that use the mechanism for
removing heat from a substance under controlled
conditions.
 It is a good example of the 2nd law of
Thermodynamics.

2. HISTORY
 The first commercial ice-making machine was invented in 1854
 In 1913, refrigerators for home use were invented
 The introduction of Freon in the 1920s expanded the refrigerator market
during the 1930s

3. THE BASIC PRINCIPLE
 Basic principle of refrigeration is simple.
 Just pass a colder liquid continuously around the
object which is to be cooled.
 This will take heat out from the object

4. COMPONENTS OF REFRIGERATOR
 Compressor
 Condenser
 Evaporator
 Throttling Device

5. COMPRESSOR
 The compressor constricts the refrigerant vapor, raising its pressure,
and pushes it into the coils on the outside of the refrigerator.
 When the hot gas in the coils meets the cooler air temperature of the
kitchen, it becomes a liquid

6. CONDENSER
 A condenser is a unit used
to condense a substance from
its gaseous to its liquid state.
 It cools hot vapors, causing them to
condense into a liquid.

7. TEMPERATURE ZONES
 −18 °C (0 °F) (freezer)
 0 °C (32 °F) (meat zone)
 5 °C (41 °F) (cooling zone)
 10 °C (50 °F) (crisper)

8. REFERENCES
 Wikipedia.org
 Thekitchn.com
 Learnengineering.org