Vapour Compression Refrigeration System: Components And Working Principle

Vapour compression is one of the most used refrigeration systems out there. In this article, I will share with you how this type of refrigeration system works.


For those who are not aware of what a refrigeration system is, here is the definition; a refrigeration system is a combination of processes performed by different components to bring a cooling effect.


Without wasting time, let me share with you what you need to know about this type of refrigeration system.


Components of vapour compression system and their functions.

The vapour compression refrigeration system has the following components;


Condenser – It contains coiled pipes and this is where the high pressure and temperature refrigerant is cooled.


The main reason why the condenser pipes are coiled is to increase the surface area of heat exchange since the refrigerant will have maximum time to move via the pipes.


Evaporator – It contains pipes that are coiled at which the liquid-vapour refrigerant at low pressure and temperature absorbs latent heat of vaporization from the body that needs to cooled.



Expansion device – Another name for expansion device is throttle valve or refrigerant control valve. The main function of this device is to allow the liquid refrigerant under high pressure and temperature to pass to the evaporator for the second cycle.


It reduces the pressure of the liquid refrigerant to its normal condition before it was expanded.


Compressor – The main function of the compressor is to compress the vapour refrigerant that was at low pressure and temperature from the evaporator.


The compression of this vapour refrigerant causes an increase in temperature and pressure.


Working principle of vapour compression refrigeration system.


Step 1:

The evaporator which contains the liquid-vapour refrigerant under low pressure and temperature absorbs latent heat of vaporization from the medium to be cooled.


When the liquid vapour absorbs enough latent heat of vaporization it changes its state from liquid to a vapour and it gets superheated at its exit to the compressor.


Step 2:

The vapour refrigerant is now superheated but it’s still under low pressure and temperature is drawn to the compressor.


The compressor compresses the vapour refrigerant which results in an increase in temperature and pressure of the refrigerant since the portion of compression energy is transferred to the refrigerant.


Step 3:

The vapour refrigerant that is under high temperature and pressure is delivered to the condenser. This is where the vapour refrigerant is cooled.


When the vapour refrigerant is cooled it changes its state from a gas to liquid.


The cooling of the vapour refrigerant is usually achieved by air or water.


Further reduction of temperature happens in the pipe work from the condenser or a liquid receiver.


Step 4:

The sub-cooled liquid refrigerant under high pressure enters the expansion device where its pressure is dropped and it’s controllably allowed into the evaporator.


When the liquid refrigerant enters the evaporator the process is repeated.


In small refrigeration systems like the domestic ones, the throttling process is achieved by the use of a short coiled capillary tube.


The control of the cold chamber is achieved by the use of a thermostat, when the temperature in the chamber is as required according to the control, the control will switch off the motor driving the refrigerator.


If the temperature in the cold chamber rises the thermostat control will switch on the motor thus the process will be repeated.


This is the complete process of the vapour compression system.


This system of refrigeration has its limitations and that is why it’s not used in some applications.


Disadvantages of vapour compression refrigeration systems

1. The initial cost is high.

The initial cost of starting this refrigeration is high since it involves the use of refrigerants.


These refrigerants are quite costly and that is what makes this refrigeration system disadvantageous.


And as time goes by the refrigerants continue to increase in price, and we will have no choice but to charge our refrigerator even if the cost is higher.


Without the refrigerant, there is no way the vapour compression refrigeration system will work.


2. It leads to environmental issues when toxic refrigerants are involved.

This is another disadvantage of the vapour compression refrigeration system.


Since it depends on the use of refrigerant to bring the cooling effect desired it’s a danger to the consumers and the environment.


If a toxic refrigerant is used e.g R21, R40 and R630 this will end up affecting the health of the consumers and the environment at large.


3. It needs strict measures.

The Vapour compression refrigeration system needs strict measures for it to work effectively.


There is a need for a constant inspection of the compressor since if it fails even within an hour there will be a huge problem.


Also, one should ensure the system is completely secured and there is no leakage of the refrigerant at any point.


This kind of system can’t stand any negligence since one single issue can temper the whole system.


Advantages of vapour compression refrigeration system.

1. The vapour compression refrigeration system needs a smaller space.

Since the system requires only a few components for it to work this makes it more suitable as it occupies a smaller space.


You don’t need a huge space to fix such a system and this makes it economical too.


When you compare it with the vapour absorption refrigeration system which you will need a space for a generator, this is way better for small spaces.


2. The refrigerant needed is at a minimum.

One of the issues people are experiencing now when it comes to the prices of refrigerants is a nightmare.


As the day goes by the prices of refrigerants keep on spiking to new levels.


The good thing about the vapour compression refrigeration system is that you don’t need much refrigerant at all.


When you fed your refrigerant in the refrigeration system the only thing you should be worried about is when there is leakage, which will waste your refrigerant.


The refrigerant is reused in this system and that is the main reason why you only need less.



3. It has a higher coefficient of performance.

In most domestic uses, people prefer to use this kind of refrigeration system simply because of its super high performance.


It fulfils the needs of many individuals thus making it super amazing for use.


With the high coefficient of performance, it doesn’t need much power at all for it to work.


And this is what everyone wants, amazing refrigeration with lower power consumption.



4. It has a wide range of operating temperatures.

Since you can control the temperatures you need in this refrigeration system you aren’t restrained to set any values you need.


This makes it more advantageous for consumers who prefer operating this refrigeration system at different temperature ranges.


The control systems that the vapour compression refrigeration system is built with are what make this control very possible.



5. It’s easier to operate and maintain.

A vapour compression refrigeration system is easier to operate and maintain simply because it has fewer and more understandable components.


The moment the refrigeration system doesn’t work you don’t need to dig deeper to check out where the problem is.


Only a few things to check on and you will eventually understand where your problem originates.


Also, when it comes to maintenance of the refrigeration system you don’t need a technician to help on that as long as you know where the components are.


This is one of the factors that makes it so advantageous for many domestic uses.


This is all about vapour compression refrigeration systems, if you have any questions or a point to add on just leave your comment.


Thanks for stopping by, see you in my next article.


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