If you are going to be working with refrigeration systems, you need to know about the different types of systems out there. All refrigerators will transfer heat in some way, but the methods that are used will vary. Each system works in a different way which is why you need to know about how each of the refrigeration systems actually works.
Mechanical-Compression Refrigeration Systems
The mechanical compression refrigeration system is the most widely used refrigeration system. This is due to the fact that it can be used in a number of different applications. The uses will include industrial refrigeration as well as air conditioning.
As the name of the system suggests, it will work by transferring heat through mechanically compressing the refrigerant. When this happens, the refrigerant is compressed into a low-pressure and cold liquid before it is turned into a high-pressure and hot gas. These systems will generally use a range of different refrigerants based on the application and maintenance of refrigeration equipment.
The refrigerant is the liquid within the system which can boil at certain temperatures and turn into a gas. There is a wide range of refrigerants which can be used in these systems. To determine which one the system uses, you will have to consult the manual.
The basis of the system is that it will move the refrigerant from the low-pressure section of the machine to the high-pressure side. The liquid refrigerant in these systems will be boiled to 40°F when on the low-pressure side of the system. At this point, it will absorb heat as it turns into vapor.
The vapor will then move to the high-pressure side of the system. Here the vapor will have a temperature of 110°F and be exposed to cooler outdoor air. This will cause the refrigerant to liquefy and the process can start again.
Absorption Refrigeration
Another AC refrigeration system that you need to know about is the absorption refrigeration system. This system will work in a similar manner to the mechanical-compression by compressing and expanding the refrigerant. However, there are some differences as the system relies on the process of absorption instead of the powered mechanical compressor.
The refrigerant that has most commonly been used in these refrigerant systems is R22. However, this is being phased out because it has been found to harm the ozone layer. The most common replacement for this refrigerant is R-410A which has a smaller environmental impact. These refrigerants are substances that other substances are drawn to and this makes them ideal for heat absorption.
The process used for absorption refrigeration starts with the refrigerant in a liquid state. It will move through the evaporator coils in the refrigeration machine. These coils will have warm air blown over them and the refrigerant will start to absorb this heat and turn into vapor.
The vapor will then travel to the condenser section of the unit which has condenser coils. These coils will have cool air running over them which allows the refrigerant to release the heat it has absorbed. As this happens, the refrigerant will turn back into a liquid and start the cycle again.
Evaporative Cooling
Evaporative cooling works very differently to the other types of systems that are commonly used. This is due to these systems rejecting the traditional refrigeration cycle which makes use of refrigerants. These systems are commonly called swamp coolers because they make use of water instead.
These systems will have water soaked pads instead of refrigerants in them. The system will have outdoor air blowing over these pads before it enters the home. The basis of this process is that the water will absorb the heat from the outside air and cool it as it enters the home.
When the heat is absorbed by the water, it will start to evaporate leading to the name of this system. The cooler air which is created by the system is channeled into the home while the warmer air is channeled out. It is important to note that these systems do not allow you to set temperatures as other systems do.
However, an evaporative cooling system will be able to reduce the temperature inside a building by 15 to 40°F. They are best suited for homes in locations that are dry such as the southwestern states of the USA. They are also cheaper to install and will only use a fraction of the energy that a traditional AC unit will.
Thermoelectric Refrigeration
This refrigeration system is completely unit as no refrigerants or water are used to create the cooling effect on the air. These systems will instead make use of an electric current and a thermocouple. This type of system is not very common because of the small cooling loads which are hard to access such as those in electrical systems.
The thermocouple used in the system is made up of 2 metal wires. These wires will be united at both ends and insulation will separate the rest of the wires from each other. When an electrical current is directed to the thermocouple, the one end will become hot and the other will become cool.
When the flow of the current is reversed, the hot and cool points will swap. The hot end of the thermocouple will generally be placed outside of the area that needs to be cooled. It will also have a heat sink attached to it to ensure that it remains at the same temperature as the surrounding air. The cool side of the thermocouple will be below room temperature and placed in the area which needs to be cooled. This point will draw the heat out of the air and ensure that the small space has been effectively cooled.
There are many different types of refrigeration systems out there, but there are 4 that are most commonly used. The system that should be used will vary depending on the application of the system and the amount of space that is available. Thermoelectric refrigeration is ideal for very small spaces while the other systems can be used in larger spaces.
