Compression chiller is actually a type of chiller or it can be said that the chiller is a part of the air conditioning system that does its job by removing heat. In fact, the chiller does not produce cold but removes heat. Because of the word chill in the name of this device, we may think that the main function of the chiller is based on the production of cold, but this is not the case.
What is a compression chiller and what is the difference with other chillers ?!
In the article What is a chiller, the types and components and how the chiller works were fully explained. Therefore, the chiller consists of a set of components of the evaporator, condenser, expansion valve, fans, pumps, compressor and absorbers (absorbers) and other items. An anthology of these items makes a variety of chillers. This means that if the main components of the compressor and evaporator chiller are condenser, expansion valve, this chiller is a compression chiller. In fact, the main difference between a compression chiller and other types of chillers is the presence of a compressor, because the presence of an evaporator, condenser, and expansion valve is the same in all chillers.
What is the function of a compression chiller?
If we want to look at the scope of tasks of a compression chiller, we must consider the tasks of any other air conditioner: temperature control and bringing it to and maintaining the air temperature, controlling humidity and creating airflow and cleaning the ambient air.
Compression chillers are usually installed on the roof or basement and engine room of buildings with any type of residential, commercial, industrial, recreational, educational and other uses to do their job. The fact that this chiller can be installed and used in all buildings and structures increases its flexibility and compatibility.
How does a compression chiller work?
The general form of compression chiller activity is such that the water entering the device, which is heated due to the activities of industrial devices or air conditioners, is brought to a low and desirable temperature for operation and by pumping water to indoor units or Industrial production units return it to the activity cycle.
How a compression chiller works are as follows:
- First, the heated liquid enters the chiller evaporator through the inlet valve, in this part, the liquid evaporates by taking heat from the environment and enters the gas phase. At this stage, the ambient heat is naturally removed and the areas that are in contact with this part are reduced in temperature.
- The chiller compressor then compresses the gas and raises its temperature, then directs it to the condenser.
- The condenser then changes the gas refrigerant to a saturated liquid. This process is a constant pressure process.
- The last stage of this cycle is inside the expansion valve, which removes the pressure from the gas refrigerant and causes it to expand. Finally, the refrigerant leaving the expansion valve is a mixture of liquid and gas that enters the evaporator.
The evaporator and condenser are the two main poles of the compression chiller that have the lowest temperature and the highest temperature in the device, respectively, so they must be well insulated against each other so as not to affect the performance. The only intermediary between the two is the refrigerant that moves between the two while doing its own work.
The whole focus of the compression chiller work is to keep the refrigerant in rotation between the different phases of the material so that it can reach its target. This is done in the temperature range between 7 and 37 degrees Celsius.
It can be said that the chiller is a self-sufficient system because it has its own source of refrigeration. This source of refrigeration does not exist in many air conditioners, such as the fan coil itself, and a factor such as a boiler or a package must supply water as a source.
Types of compression chillers
Compression chillers can be divided into different categories. These chillers are divided into two categories, cold air or cold water, depending on how their condenser works. This means that some of the condensers are cooled with water and some with gas.
Cooling water compression chillers require a cooling tower to take over part of the process, but cooling air chillers do not require a cooling tower. In contrast, cooling air in condensing chillers is such that fans are placed around the condenser to absorb heat. This form of cooling actually affects the entire chiller system.
Another type of division is based on compressor chillers; In this way, the shape and operation of compression chiller compressors divide them into four categories of compression chillers:
- Scral or helical
- Screw or spiral
- Piston or impact or reciprocating
- Centrifuge or centrifuge
Each of these chillers incorporates a different type of compressor appearance and performance. Thus, if we hear the name of cold water screw compression condenser, we can see that in the first place, this compression chiller is cooled by water and then its compressor is in the form of a spiral or screw.
Depending on the compressor, each type of chiller can be combined with air-cooled or water-cooled condensers to create a specific type of compression chiller.
Compression chillers based on compressor
Scral or helical
In this type of compression chiller, there are two screw gears, one fixed and the other movable. Refrigerant condenses between the two gears. The sound of this type of compressor is usually low and does not have many moving parts, has a long life and does not require high maintenance.
Screw or spiral
In this type of chillers, the refrigerant compression gears are helical. This type is also durable and long life and produces little sound. One of the advantages of screw compressors in compression chillers is its high capacity control capability.
Piston or impact or reciprocating
Reciprocating compressors perform both suction and discharge operations in one go, compressing the refrigerant. These types of compressors can be considered as an element for a larger set and combined with other factors to build a stronger set. The price of a reciprocating compressor is lower than other compressors.
Centrifuge or centrifuge
As the name implies, this compressor compresses the refrigerant by spinning at high speed and centrifugal force. The noise and vibration produced in chillers with this compressor are much less, and it is also easier and less expensive to maintain this type of chiller compressors.