Imagine the following scenario.
It’s summer. You’ve just returned home from a long day at work.
Temperatures in recent days have reached a new record for this time of year.r
The air is so hot that it is difficult to breathe.
Heat comes out of the hot cement, making the atmosphere even more overwhelming.
You open the door of the house and go inside.
Despite the high temperatures outside, the air inside your house is cool and comforting.
The atmosphere in your home is welcoming and cool, as if there were no traces of excessive heat in it.
Despite the heat outside, your home offers you a place where you can relax without enduring the harsh conditions of excess heat.
And the existence of this blessing is due to the refrigeration cycle and its benefits.
There are various methods by which the cooling process can be accomplished.
But the basic principles by which it is born are the same.
Because of their benefits, these principles are used in many countries and various industries.
Many people do not know how these processes work despite their importance and widespread use.
That is why we set out on a mission to cast a ray of light over this gloomy cloud of ignorance.
To accomplish this noble mission, we must begin with the beginning.
How does refrigeration work?
To understand how a refrigeration cooling cycle works, we must first determine what it represents. By the end, you’ll be an expert on the parts and components of a refrigeration cycle system.
A refrigeration process can be defined as a process whose main purpose is to reduce the temperature to a certain level and keep it there.
The reference temperature is that of the environment.
So the main purpose of a cooling cycle is to lower the temperature of an object or environment below the ambient temperature.
This process can also be called ” artificial cooling. “
An HVAC expert will tell you that it is impossible to produce a cold.
All you can do physically is remove heat from the environment or object, which will cause the temperature to drop.
Generally speaking, a refrigeration cycle will take heat from one environment and remove it to another place.
It will eventually increase the temperature in the environment where all the heat is removed.
It leads us to conclude that a refrigeration system aims to move heat from a lower temperature to a higher temperature.
This process has many applications in everyday life and the industrial field.
For example, preserving perishable foods is achieved through this cooling process.
Maybe the cooling of the air in a house is done with the help of this method. It’s to offer a higher degree of comfort.
Refrigeration cycle explained
Now that we’ve learned more about what a refrigeration cycle is and what it can be used for, it’s time to dig deeper.
Now, let’s look at how a cooling cycle works and explain everything you need to know about it.
As I just mentioned, a refrigeration cycle is a machine that can extract heat from one environment and eliminate it in another environment.
If the main purpose of this machine is to cool an environment or an object, it is called a “refrigerator.”
Heat is bound to obey a certain set of laws of physics, like any physical property.
One of these laws of physics is the second law of thermodynamics.
According to this, a quantity of heat can’t move normally from a colder environment to a warmer environment.
Here comes the role of a refrigeration cycle.
It does not allow heat transport to be done by itself because that would be impossible.
External help is used to bring this heat transport to a successful end.
According to the second law of thermodynamics, this heat transport can be achieved if an external auxiliary force intervenes and offers a helping hand.
And that external force is a motor.
Normally, the role of a heat engine is to produce heat using a type of fuel.
This heat engine can be taken and modified to work the other way around.
Instead of removing heat by processing fuel, it can absorb heat and remove it in another environment.
It will absorb heat from a lower temperature environment and move it to a higher temperature environment.
Hence the name of this heat pump device.
This process can only be done with the help of a motor, which is external help.
That engine will need fuel to carry out this process.
But from what we’ve learned so far, a refrigerator has the same effect.
It absorbs heat from a lower temperature environment and removes it in a higher temperature environment.
We can deduce that the principle of operation of a cooling cycle is the same as that of an inverted heat engine.
A diagram explaining the operational process of a refrigeration cycle is shown below.
Types of refrigeration
There are several ways in which refrigeration can be done.
It gives rise to a variety of types of cooling cycles, such as:
- Mechanical compression refrigeration
- Steam compression
- Steam absorption
Now let’s look at each method and the few details that characterize them.
1. Mechanical compression
Refrigeration systems that use this method are often used for industrial and commercial purposes.
Air conditioners can also use this system.
A centrifugal force compresses the refrigerant vapors during this cooling process.
A reciprocating compressor creates this compressive force.
These mechanical systems have the disadvantage that they have a very high energy consumption.
This increased power consumption is necessary for the optimum operation of the compressor and pumps.
The optimal operation of these parts is necessary for the cooling water circuit.
After the vapors have passed through the compression process, they are passed to a condenser.
Its role is to condense the vapors.
After this process, the condensed steam is expanded into an expansion valve.
Upon completion of this expansion process, the effect arises.
2. Evaporative cooling
This refrigeration system uses the properties of water to cool the amount of air introduced from outside inside the house.
The air taken from outside the house is passed through a filter before entering the house’s atmosphere.
Water is constantly pumped into that filter.
The hot air that passes through that filter loses its amount of heat contained under the action of water.
This process is called “evaporative cooling.”
The advantage of this cooling system is that it needs a small amount of electricity to operate in optimal conditions.
In addition, it has the benefit of introducing a constant amount of fresh air inside the house.
This refrigeration system is ideal for raising the humidity level in a dry environment.
3. Absorption refrigeration
This system uses a heat source to obtain the energy needed to operate the refrigeration process.
This source can be powered by solar energy or fuel.
The optimum operation of this system requires the existence of two coolants.
The first coolant is passed through the evaporative cooling process.
The first coolant is absorbed into the second one upon completing this process.
Now the heat source comes on stage. It is used to reset the two coolants to their original state.
The principle of this cooling system is often used in recreational vehicles and caravans.
Peltier’s principle is the basis of how this system works.
This principle creates a change in temperature through heat transfer between the junctions of the two conductors.
A voltage is passed through the space between the two conductors for this process to work.
In this way, an electric current is created.
When this electric current passes between the junctions of the two conductors, the heat is removed at one junction.
It is how the cooling process takes place.
The amount removed is absorbed by the other junction.
5. Steam compression
This cooler uses a coolant that is in a closed environment.
In this closed environment, the coolant is circulated and is passed through 4 different stages.
During these stages, the coolant is constantly compressed and expanded.
In this way, the coolant is switched from vapor to liquid alternately without leaving the closed environment.
The coolant absorbs heat from the cold environment or object during the evaporation phase.
In this way, the environment or object is cooled.
The absorbed heat is used to carry out the evaporation process further.
The amount absorbed is moved to the external environment during the condensation process.
It creates a cooling effect in the coolant.
This refrigeration system is often used in buildings and cars.
6. Steam absorption
This cooling system consists of several components, such as:
- expansion valves
- reducing valves
This type of cooling system is often used in areas with no access to a large amount of energy available for consumption.
This system is often used in areas that require large-scale air conditioning.
Vapor absorption refrigeration uses heat energy to carry out the cooling process.
This cooling mode is much cheaper than steam compression refrigeration.
The installation of this cooling system is optimal if it is done in an area where heat energy is valid at a low price.
Vapor absorption cooling systems are often used in steam power plants.
Now that we know what refrigeration is, how it works, and its types, it’s time to look at another topic.
Namely, the components that make it possible to carry out the process.
Of course, each type of refrigeration process can use different components.
Among all the types of refrigeration processes, there are 4 frequently used components.
And they are represented by:
- expansion device
Let’s take a closer look at these pieces and find out a little about each one.
1. The compressor
The first step in the process is compression.
The purpose of the compressor is to increase the operational gas pressure level.
The refrigerant, a gas, enters the compressor at low pressure and temperature levels.
After leaving the compressor, the refrigerant is at high pressure and temperature.
The refrigerant compression method can be performed in several ways.
Because of this, various types of compressors can be used to carry out the refrigeration process.
Some of the most commonly used types of compressors are:
- reciprocating compressor
- scroll compressor
- rotary compressor
2. The condenser
The condenser is one of the two parts in a cooling cycle capable of exchanging heat.
Do you remember that gas at high pressure and temperature levels at the compressor?
Well, it will be removed by the compressor inside the condenser.
The main purpose of the condenser is to remove excess heat from the gas.
After this heat dissipation, the gas will condense and turn into a liquid state.
Keep in mind that the condenser only removed the heat from the gas. The pressure level was not affected by it.
It means that the gas has been transformed into a liquid at low temperature and high-pressure levels.
After the condensation process is complete, the liquid will be transported to the expansion device.
3. Expansion device
This device has several designs.
The most popular designs used usually include the following components:
- fixed holes
- thermostatic expansion valves
- thermal expansion valves
- electronic expansion valves
The role of an expansion device is the same, regardless of its components and design.
And that is to lower the pressure level of the liquid after it leaves the inside of the condenser.
This pressure drop will cause the liquid to start boiling.
This process will lead to a two-phase mixture.
This rapid change of state also has a specific name.
The role of this process is to prepare the fluid for the events in the next component.
4. The evaporator
Do you remember that I just mentioned that the condenser is one of the two components in a refrigeration cycle capable of exchanging heat?
Well, the evaporator is the second component that can do this process.
Its name is a clear indicator of his role.
It carries out the final activity of a cooling cycle, that of absorbing heat.
This process of absorbing heat begins when the refrigerant enters the evaporator in its liquid form.
This liquid will enter the evaporator at low pressure and temperature.
After that, a fan will pump air on the evaporator fins.
The heat from that air will be absorbed by the evaporator directly into the refrigerant.
In this way, the air temperature will drop and cool.
After this process is completed, the refrigerant is sent back to the compressor.
After that, the whole refrigeration cycle will start again.
The simplest cooling cycle of all is described above, which involves only 4 components.
Due to the small number of components, it can be declared the simplest refrigeration cycle.
The components it owns are:
– expansion device
A refrigeration cycle can also be called a “heat pump cycle.”