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In defining what a chiller is, it should be noted that a chiller is actually a type of air conditioning device that may not produce cold, contrary to our initial idea of the word chiller. In fact, the work of the chiller; This large device, which is a complex and noisy set, cools and provides the right temperature for the air conditioning devices, but it does so not by producing cold, but by removing heat. For this reason, the liquid-cooled by the chiller returns to the cycle and can be used for the ventilation system; In short, chillers are heat removal devices.
Chillers are used for both industrial and air conditioning purposes. Industrial uses mostly include maintaining the temperature of tools and devices during processes and mechanisms, and the air conditioning system is more about keeping cool and controlling humidity in large residential or commercial and office buildings. The chiller is usually installed on the roof or in the basement and plays the most important role in providing cooling to the building in summer. In the previous articles on what is an air conditioning system in general, sufficient explanations have been provided on how this system works.
The chiller itself generates a source of cold or heat and does not end with gas and liquid circulating devices alone. This means that the source itself, which may previously have been a separate boiler or package to provide the water needed for the fluid in the devices inside the system, has now become a member within the chiller itself.
The features and, in fact, the advantages of a chiller can be summarized as follows:
- High capacity
- Carrying a cold or heat generator
- Chiller ducting and piping with different materials and compatible with the needs
- Possibility of separate control of each channel, although the chiller is a mother system that accommodates all channels.
- Low noise production
- Low energy consumption
What are the components of a chiller?
The chiller is a single set consisting of many different components. The different parts of the chiller are as follows:
- operator
- Compressor
- condenser
- Storage tank
- pump
- Fans
- Expansion valve
- Control panel
- attractive
- air conditioner
- Generator
Of course, it should be noted that this set is the general components of chillers, and each chiller has different limits from this list, depending on its type. In this way, the components of each type of chiller are different from the components of another chiller. But in between, the evaporator, condenser and expansion valve are all common.
What are the types of chillers and how does each type work?
After a general acquaintance with what a chiller is and how it works, we can introduce its types.
You can simply go through the cycles inside the chiller to get acquainted with how it works. It can be said that one of the main cycles and currents in the chiller is the refrigerant movement between the condenser and the evaporator. The second cycle is the connection of the evaporator and all the components of the building through the refrigerant, which is in reciprocation between the two. The third cycle also occurs between the condenser and the cooling tower.
The whole focus of the chiller operation is to keep the refrigerant in rotation between the different phases of the material. This refrigerant has a high heat capacity and therefore can be in constant rotation between different phases of the material. This is done with the help of the sciences of thermodynamics and heat transfer.
Chillers are produced in two types of absorption and compression. These names actually go back to how they work. In this way, the absorption chiller works with thermal energy and the compression chiller works with electric energy.
What is a compression chiller?
A compression chiller works by having the condenser chiller first compress the gas and then direct it to the condenser to liquefy the gas. The liquid then enters the evaporator, which has less pressure than before. This reduction causes the liquid to evaporate and, following the heat required to evaporate from the cooling section, causes cold in the areas that are in contact with the cooling section.
Since the evaporator and the condenser each contain cold water and hot water separately, there is no need to worry about them coming together and affecting each other, because the condenser and the evaporator are well insulated against each other and the only way to communicate between They are a refrigerant that has a chilling effect on it.
As mentioned, there are three cycles between the components of chillers. But the components of a compression and absorption chiller are different. Therefore, the main and first cycle in a chiller is compression between the evaporator, compressor, condenser and expansion valve.
Compression chillers are divided into two categories: cold water chillers and air-cooled chillers. Of course, there is another division for compression chillers based on their compressors: four types
- Scral or helical
- Screw or spiral
- Piston or impact or reciprocation
- And centrifuge or centrifuge
Therefore, when we talk about screw cold water chiller, we mean a compression chiller of cold water with a screw compressor.
Cool water screw chiller
In a screw or spiral chiller, water is used as the refrigerant, and the job of the chiller is to carry the refrigerant, which is water, to different phases. In fact, the name of this chiller can be a water-cooled compression chiller. Screw cold water chiller compressor consists of two shafts or a helical shaft that compresses the refrigerant with its gradual rotation. Coldwater chiller means that the condenser part of the chiller is cooled by water. For this reason, in a cold water chiller, the water is cooled by a device called a cooling tower or cooling tower.
Cool water screw chillers produce less noise pollution, but at the same time in terms of control, the operator can have high control over the chiller. Also, in compression chillers, it is possible to control air pressure and oil pressure.
Cool screw air chiller
The task assigned to an air chiller, like that of other chillers, is to cool the water in a closed circuit and then deliver or pump it to all other parts of the building or structure. The cool air screw chiller, like the water chiller of the same model, works by one or two spiral axes. These helical shafts, called rotors, place the gas entering the chiller’s suction section across their grooves and begin to move at a predetermined, coordinated speed to compress the gas.
Since we know what a cooling tower is, and since it is the air cooler in the screw chiller, it is the air that cools the condenser, so there is no need for a cooling tower. In this way, the fans installed above the chiller draw air from the condenser tubes and cool it. For this reason, this type of chiller is called an air-cooled chiller because its condenser is cooled by air.
Centrifugal blue chiller
The term centrifuge refers to how the chiller compressor works. So a centrifugal water chiller is a chiller with a compressor that works like this:
The motor inside the compressor moves the impeller inside the compressor through the intermediate rods and gears. The impeller rotates the refrigerant inside the compressor to provide centrifugal force, which in turn increases the motion and temperature of the refrigerant particles. In fact, the three main parts of the compressor are a centrifugal water chiller; They are impellers, inputs and diffusers.
Centrifugal water chillers are one of the first examples of chillers produced in the world and due to their simple structure, they are one of the most common examples of water chillers.
What is an absorption chiller?
Absorber, pump and heat generator are used instead of the compressor in an absorption chiller. In fact, these three factors have replaced the compressor factor. The most commonly used refrigerant in refrigerant chillers is lithium bromide. The absorption chiller works in such a way that water vapour is absorbed by lithium bromide and this vapour flows between the gas and liquid phases and finally, for its evaporation, it takes the heat of the cooling medium and reduces the temperature of the same medium.
There is another category for chillers and it depends on the refrigerant phase in the chiller: cold water, air-cooled and evaporative chillers are different types of chillers in this regard.
In absorption chillers, the main and first cycle takes place between the evaporator, absorber or absorber, and the pump and heat exchanger, condenser and expansion valve.
Steam absorption chiller
Steam Fired Absorption Chiller uses heat instead of electrical energy to supply its energy. This type of supply can be beneficial to the environment, because it is possible to use the thermal energy of industrial processes, and thus a kind of recycled energy is used to meet the needs of the absorption chiller.
Inside the steam absorption chiller, instead of the compressor used in compression chillers, a heat compressor such as a generator or absorber is used or a pump and heat exchanger. In this type of chiller, water vapour enters the condenser, is cooled by the environment and then enters the liquid phase. This liquid re-enters the evaporator part which has low pressure. As a result, the boiling point of the substance drops and begins to boil. In this way, the environment that has been trying to heat the material to help it boil cools down.
Direct heat absorption chiller
Direct fire or direct flame absorption chiller uses a flame to supply its thermal energy. Therefore, all internal components of a direct flame chiller must be resistant to high temperatures. This feature makes the chiller itself fully prepared for heavy operations in difficult conditions and not damaged.
The adsorbent inside this chiller is lithium bromide and the refrigerant inside is water. The use of direct heat absorption chiller, in addition to saving energy consumption, also leads to saving gas fuel consumption, water vapor and hot water. Since the efficiency of this type of chillers is very high, they have the capacity to perform heavy activities and produce high heat and are suitable for industrial use.
Also, since heat absorption chillers have direct access to the heat generator on their own, they can be used to generate both cold and heat in summer and winter.
Comparison of absorption and compression chillers
So far we have found that steam and direct heat absorption chillers are both absorption chillers.
Perhaps the most important advantage of absorption chillers over compression chillers is their cost savings and energy consumption. With absorption chillers, it saves on electricity and other electronic installations in case of emergency, on the cost of electrical services and on electronic energy consumption. This is because, as mentioned, absorption chillers use thermal energy to provide a source of cooling.
Also, absorption chillers have less vibration and produce less noise and environmental pollution. In addition, these types of chillers do not use harmful refrigerants and are involved in reducing environmental pollution and greenhouse gases.
On the other hand, we can point out the most important advantages of compression chillers such as cold water and air-cooled screw and centrifugal chillers:
The compression chiller itself is slightly cheaper and requires less raw material. This means that the amount of water required to operate a compression chiller is less than an absorption chiller. The volume and weight of compression chillers are less than absorption chillers.
Since the compression chiller works with several compressors, if one of the compressors fails, the performance of the whole chiller will not be disturbed and the chiller will continue to work with the other compressors. It is also optional to disable a number of compression chiller compressors so that not all compressors are operating for the lower capacity required and only the number of compressors that have sufficient capacity to operate. In addition, this type of structure also increases control over the device.
