How a Refrigerator Works

Last updated: October 20th, 2022

The refrigerator is one invention that has made our lives unquestionably easier. The cold temperature inside slows or minimizes the growth of bacteria in foodstuff. This allows us to preserve food and use them again. Naturally, heat flows from higher temperature to lower but in refrigerators, it happens the opposite route.

There are many kinds of refrigerators in the market like Built-in, Wine Cooler, Bottom Freezer, etc. However, despite the design differences, all of them have the same basic parts and use the same principle. If you have ever wondered how this complex-looking piece of machinery works, then give this article a read.

Working Principle

The working of a refrigerant is a simple process, which is the removal of heat from one region(fridge) and deposition to another(outside). This removal and absorption of heat are done by a working fluid known as Refrigerant. One such example is Freon.

Gases when compressed get hot and become cooler when allowed to expand. The refrigerant along with some other components contributes to keeping the interior temperature cool.

Clausius Statement

The refrigerator is basically a heat engine in reverse. It performs eat transfer from a cold reservoir to a hot one. We know that this is physically impossible. The Clausius law of Thermodynamics states that it is impossible to build a device that transfers heat from lower to higher temperatures.

Since the refrigeration cycle is against this law, it is not a spontaneous process. As a result, we need to supply work to make it feasible.

Parts of a Refrigerator:


The compressor is located at the bottom of the refrigerator in the back. The compressor compresses the refrigerator fluid by applying pressure and pumps it throughout the refrigerator. Thus the refrigerant changes from a low temperature to a high-temperature gas. Any issues with the compressor will cause cooling problems in the refrigerator.


The condenser can be identified as a coiled set of tubes with fins. Condenser Coils are usually located at the back of the fridge. They are quite hot to touch because this is where the heat rejection takes place. The vapor refrigerant from the compressor enters the condenser and changes to a liquid while rejecting heat.

Expansion Valve

Expansion Valve is a tiny device that is responsible for controlling the flow of liquid into the refrigerant. There is a pressure drop in the expansion valve as too much liquid entering the evaporator can impact its working. It basically separates the high and low-pressure sides in a refrigeration system.


The evaporator is where the heat absorption takes place. The evaporator is located near the freezer compartment and consists of metal tubes with fins. The liquid refrigerant enters the evaporator and absorbs heat from the stuff inside, and as a result, the liquid turns into a vapor refrigerant.


Refrigerant or Coolant is the fluid that is actually responsible for keeping the refrigeration cycle going. Usually, it is a chemical that can easily alternate between a cool liquid and a hot vapor. Initially, CFCs were widely used as refrigerants but they were responsible for issues like Ozone depletion. As a result, CFCs were banned, and now Ammonia, R-290 are used commonly.


The thermostat is responsible for maintaining the required temperature. It does this by monitoring the temperature and turning the compressor on and off. If the interior temperature is fairly cold, then the compressor is turned off. If the temperature is hot, it switches on the compressor and the cooling cycle starts again.

Defrost System

Helps to remove the excess ice in the freezer. It can be done manually by a button or automatically.

Energy use in a Fridge

The compressor requires a current to pump refrigerant throughout the fridge. When the fridge is at the optimum temperature, the compressor turns off. However, if the temperature rises, then the compressor again goes into action.

The motor in the condenser fan needs electricity and will be on whenever the compressor is working. The condenser fan cools the refrigerant fluid as it passes through the coils, thus removing the heat absorbed from the interior and in the process returning the refrigerant to a liquid state.

The motor in the evaporator fan is always in the on state and works even when the compressor and condenser are off. The evaporator fan maintains a constant airflow in the interior. This helps the refrigerant in the evaporator coils to absorb heat.


We hope this article would have helped you gain an insight into the working of the refrigerator. Also, we have mentioned the functions of the different parts and therefore, the next time you are in the market for a refrigerator, you would have an idea of what you need. Hope this article will solve some of your doubts and provide you some valuable information.


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