How Does a Refrigerator Work

Refrigerator is the most frequently used home appliance. Ever wondered how a refrigerator cools the food items inside it? Read on to understand how a refrigerator works...
You will be surprised to know that refrigerators use heat to keep the food items at a low temperature. Cooling helps to keep the food fresh for a longer time. Refrigeration and freezing are the modern methods of preserving food items. Previously, food was preserved using various methods of preservation like salting and pickling. The working of a refrigerator is governed by laws of thermodynamics. Let us understand how a refrigerator works.

Basic Working Principle

The basic principle used for refrigeration is: Expansion of a gas, reduces its temperature.

The second principle is: Second Law Of Thermodynamics: When two surfaces of different temperatures come in contact with each other, the surface that is at higher temperature cools and the surface at lower temperature warms.

Parts of a Refrigerator

The mechanism used to keep the temperature inside the refrigerator cool involves different components that perform different functions. The different parts and functions of the refrigerator are listed below,

Refrigerant: This is the substance that performs the cooling function in the refrigerator through the changes in its temperature and pressure. The refrigerant usually used is ammonia or HFCs. Earlier, freon was used as a refrigerant. The liquid used in the refrigerator evaporates at a very low temperature and results into a freezing temperature inside the refrigerator.

Evaporator: It is the part that absorbs the heat inside the refrigerator with the help of the evaporating liquid refrigerant.

Heat Exchanging Pipes: The entire unit of the refrigerator is surrounded by a series of heat exchanging coils. These coils carry the refrigerant from one part of the refrigerator to the other. Most of the heat exchanging pipes are placed behind the compressor.

Compressor: It is a heavy metal device that is powered by a motor and compresses the refrigerant. The main function of the compressor is to raise the pressure and thus, the temperature of the refrigerant gas.

Condenser: It is a part of the refrigerator that condenses the vaporized refrigerant (converts into liquid form) and reduces its temperature.

Expansion Valve: The expansion valve reduces the pressure on the liquid refrigerant. Usually the expansion valve is made of thin copper coil.

Working of a Refrigerator

The working of the refrigerator is a cyclic process that comprises changes in the temperature and pressure of the refrigerant. Given below is a step-by-step explanation of the working of a refrigerator.
  • The refrigerant gas is passed through a compressor. Here, the gas is compressed and thus the pressure on it increases. The temperature of the refrigerant gas in turn increases as a result of the increased pressure and it takes the form of superheated vapor.
  • The refrigerant passes through the heat exchanging pipes and releases heat to the surroundings. Thus, the refrigerant cools down due to the loss of heat to the surroundings.
  • As the refrigerant passes through the condenser, its temperature reduce. However, the pressure on the refrigerant remains the same. Due to the reduction in its temperature, the refrigerant gets converted into its liquid form.
  • The expansion valve causes a sudden reduction in the pressure on the refrigerant. Some of the refrigerant evaporates and expands. This expansion results in the lowering of the temperature of the refrigerant.
  • During the evaporation of the liquid refrigerant, it is present in the evaporator, which absorbs the heat from the foodstuffs kept in the refrigerator and thus, cools them. The second law of thermodynamics is used here.
  • The refrigerant again heats up to form a gas. This refrigerant, which is now in the gaseous form, again enters the compressor and the cycle repeats.
This was all about how a refrigerator works. From the above discussion, we can conclude that refrigeration is the result of the transfer of heat from one place to another, with the help of expansion and compression of the refrigerant.
Last Updated: October 1, 2011
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