What is the working principle of refrigerator? How Refrigerator works

Today everybody is interested in knowing about the working principle of refrigerator and how the refrigerator works. Nowadays, Refrigerator is very important, it has become a necessity for people. In the past era, food or other things could not be kept for a long time due to the lack of a refrigerator, but today we store food and other things for a long time in the refrigerator.

First of all, we know about the refrigerator then we know how a refrigerator works and what is its working principle of refrigerator.

What is Refrigerator?

A Refrigerator is a household appliance that is used for keeping food and things cold. The refrigerator consists of a thermally insulated compartment and a heat pump.

Generally, the temperature of the refrigerator keeps at or below 4° C because the Best temperature range for perishable food storage is 3 to 5° C.

How does the Refrigerator work?

The transfer of heat from a low-temperature medium to a high-temperature is the basic refrigerator working principle. Lower temperatures reduce the reproduction rate of bacteria, therefore it reducing the rate of food waste.

Refrigerators, like heat engines, are cyclic devices. The working fluid used in the refrigeration cycle is called a refrigerant. 

Refrigerant

This is the most important thing in a refrigerator. Also known as the coolant, it is the liquid that keeps the refrigeration cycle running.

In fact, it is a specially developed chemical capable of alternating between being a hot gas and a cold liquid.

What is Refrigeration?

The term refrigeration means removing heat from an enclosed space or from a substance for the purpose of lowering the temperature. Energy in the form of heat is removed from a low-temperature reservoir and transferred to a high-temperature reservoir. The work of energy transfer is traditionally driven by mechanical means, but can also be driven by heat, magnetism, electricity, laser, or other means.

Components of Refrigerator

The most frequently used refrigeration cycle is the vapour-compression refrigeration cycle, which involves four main components :

compressor – The compressor is the pump that enables the flow of the refrigerant. It raises the temperature and pressure of the refrigerant.

condenser – condenser is a heat exchanger used to condense a gaseous substance into a liquid state through cooling. A refrigerator uses a condenser to get rid of heat extracted from the interior of the unit to the outside air.

expansion valve – It controls the amount of refrigerant released into the evaporator and aims to control the superheat of the refrigerant that flows out of the evaporator to a constant value.

evaporator – An evaporator is a device in a process used to turn the liquid form of a chemical substance into its gaseous form/vapour. As the refrigerant turns from a liquid into a gas through evaporation, it cools the area around it, producing the proper environment for storing food.

Working principle of refrigerator

The refrigerator works on the principle of the second law of thermodynamics namely the Clausius Statement.

The Clausius statement is expressed as follows:

It simply states that a refrigerator cannot operate unless its compressor is driven by an external power source, such as an electric motor.

The second principle that works in a refrigerator is that when you have two things that are different temperatures that touch or are near each other, the hot surface becomes cold and the cold surface becomes hot. This is called the second law of thermodynamics.

The detailed process of refrigerator working principles below are discussed:-

The refrigerant enters the compressor as a vapour and is compressed to the condenser pressure. 

It leaves the compressor at a relatively high temperature and cools down and condenses as it flows through the condenser's coils by rejecting heat from the surrounding medium. 

It then enters a capillary tube where its pressure and temperature drop drastically due to the throttling effect.

The low-temperature refrigerant then enters the evaporator, where it evaporates by absorbing heat from the refrigerated space. 

The cycle is completed as the refrigerant leaves the evaporator and re-enters the compressor.

In a household refrigerator, the freezer compartment where heat is absorbed by the refrigerant serves as the evaporator, and the coils usually behind the refrigerator where heat is dissipated to the kitchen air serve as the condenser.

How to find the efficiency of the Refrigerator

The efficiency of a refrigerator is expressed in terms of the coefficient of performance (COP), denoted by COPR. 

COPR = Desired output/Required input

            = QL /Wnet,in

The value of COPR can be greater than unity. That is, the amount of heat removed from the refrigerated space can be greater than the amount of work input.

What is the difference between a fridge and a freezer?

The main difference is the temperature controller, the fridge is designed to keep food between 0 and 5 °C, freezer is designed to keep food at minus 18 degrees for long-term storage. The fridge will have storage areas for different food types, and the freezer has a temperature for everything.

Uses of Refrigerator

• The refrigerator is used for storing Fruits and Vegetables.
• The refrigerator is used for storing leftover food.
• The refrigerator is used for storing dairy products.
• The refrigerator is used for storing eggs and meat.
• The refrigerator is used for storing bread and bakery.

Industrial Application of Refrigerator

• The refrigerator is used in the Chemical and Petrochemicals industry.
• The refrigerator is used in pharmaceuticals.
• The refrigerator is used for food and beverages.
• Refrigerators used in Data centres.

If you are interested to know the Working principle of a Washing Machine click here

If you are interested in knowing the principle of Air conditioners then click here